drafts: css3-page/Overview.src.html@0dff950123a2

[css3-page] Rewrite page selector specificity for multiple pseudo-classes.

Update to Selectors 4 language, while we’re at it.

     1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">

     2 <html lang="en">

     3 <head>

     4 <title>

     5 CSS Paged Media Module Level 3

     6 </title>

     7 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">

     8 <link href="../default.css" rel="stylesheet" type="text/css">

     9 <link rel="stylesheet" type="text/css" href="http://www.w3.org/StyleSheets/TR/W3C-ED.css">

    10 <style type="text/css">

    11   .keyword { font-weight:bold }

    12   .equation { padding: 2% }

    13   table.equation {text-align:center}

    14   td, th { vertical-align: top }

    15   pre { font-size: 1em; }

    17   #margin-values { border-collapse: collapse; }

    18   #margin-values td,

    19   #margin-values th

    20   {

    21                 padding: 0.2em;

    22                 border: thin solid black;

    23   }

    25   .property-list

    26   {

    27                 border: 1px solid black;

    28                 padding: .2em;

    29                 margin-top: 2em;

    30   }

    32   .property-list td

    33   {

    34                 border: 1px solid black;

    35                 padding: .1em;

    36   }

    38   .editorial

    39   {

    40                 display: block;

    41                 font-family: arial, helvetica, sans-serif;

    42       font-size: 80%;

    43       margin-left: .5in;

    44       margin-right: 1in ;

    45       padding: 0.125in;

    46       background: #FFFFDD ;

    47   }

    49   .editorial:after { content: "Ed."}

    50   .RFC2119

    51   {

    52                 text-transform: lowercase;

    53                 font-style: italic

    54   }

    56   em em.RFC2119

    57   {

    58                 text-transform: lowercase;

    59                 font-style: normal

    60   }

    62   table.page-sizes

    63   {

    64                 border: thin solid;

    65                 margin-top: 1.5em;

    66   }

    67   table.page-sizes td

    68   {

    69                 border: thin solid;

    70                 padding: .5em;

    71   }

    72   table.page-sizes th

    73   {

    74                 border: thin solid;

    75                 padding: .5em;

    76                 background: #ffffaa;

    77   }

    79 </style>

    80 </head>

    81 <body>

    82 <div>

    83 <div class="head">

    84 <!--logo-->

    85 <h1>CSS Paged Media Module Level 3</h1>

    86 <h2 class="no-num no-toc" id="w3c-working">[LONGSTATUS] [DATE]</h2>

    87 <dl>

    88   <dt>This version:</dt>    <dd><a href="http://dev.w3.org/csswg/css3-page/">http://dev.w3.org/csswg/css3-page/</a></dd>

    89     <!-- <dd><a href="[VERSION]">http://www.w3.org/TR/[YEAR]/WD-[SHORTNAME]-[CDATE]</a></dd> -->

    90   <dt>Latest version:</dt>    <dd><a href="http://www.w3.org/TR/css3-page">http://www.w3.org/TR/css3-page</a></dd>

    91   <dt>Previous version:</dt>    <dd><a href="http://www.w3.org/TR/2004/CR-css3-page-20040225/">http://www.w3.org/TR/2004/CR-css3-page-20040225/</a></dd>

    92   <dt>Editors:</dt>    <dd>Melinda Grant, Hewlett-Packard</dd>

    93     <dd>H&aring;kon Wium Lie, Opera Software</dd>

    94     <dd>Elika J. Etemad, Hewlett-Packard</dd>

    95     <dd>Simon Sapin, Kozea</dd>

    96 </dl>

    98 <!--copyright-->

   100 </div>

   101 <hr title="Separator for header">

   103 <h2 class="no-num no-toc" id="abstract">Abstract</h2>

   105 <p>This module describes the page model that partitions a flow into pages. It

   106 builds on the <a href="http://www.w3.org/TR/CSS21/box.html">Box model module</a> and introduces

   107 and defines the page model and paged media. It adds functionality for

   108 pagination, page margins, page size and orientation, headers and footers,

   109 widows and orphans, and image orientation. Finally it extends generated content

   110 to enable page numbering and running headers / footers.</p>

   112 <!-- "Status of this document" -->

   114 <h2 class="no-num no-toc" id="status">Status of this Document</h2>

   116 <!--status-->

   118 <p>This document contains the <abbr title="Cascading Style Sheets">CSS3</abbr>

   119 Paged Media Module W3C Last Call <a href="/2005/10/Process-20051014/tr.html#RecsWD">Working Draft</a> of [DATE]. The

   120 Last Call period ends on <span class="fudge">TBD</span>.</p>

   122 <p>Expected next revision to this document is another LCWD, due to the

   123 substantive changes to page-margin box sizing and other areas that are now

   124 specified with more precision.</p>

   126 <p>The <a href="lc2_issues.htm">Disposition of Comments</a>

   127 document contains the current issues list and responses to input received

   128 during this Last Call period.</p>

   130 <h2 class="no-num no-toc" id="contents">Table of Contents</h2><!--begin-toc-->

   131 <!--end-toc-->

   132 <!-- "Introduction" -->

   133 <h2 id="intro">Introduction</h2>

   135 <p>Paged media (e.g., paper, transparencies, photo album pages, pages

   136 displayed on computer screens as printed output simulations) differ from

   137 <a href="http://www.w3.org/TR/CSS2/media.html#continuous-media-group">continuous media</a>

   138 in that the content of the document is split into one or more discrete

   139 static display surfaces. To handle pages, CSS3 Paged Media describes how:</p>

   141 <ul>

   142   <li><a href="#page-breaks">page breaks</a> are created and avoided;</li>

   143   <li>the page properties such as size, orientation, margins, border, and

   144   padding are specified;</li>

   145   <li>headers and footers are established within the page margins;</li>

   146   <li>content such as page counters are placed in the headers and footers; and</li>

   147   <li>orphans and widows can be controlled.</li>

   148 </ul>

   150 <p>This module defines a <a href="#page-model">page model</a> that specifies how a

   151 document is formatted within a rectangular area, called the

   152 <a href="#page-box-page-rule">page box</a>, that has finite width and height.

   154 <p>Although CSS3 does not specify how user agents transfer page boxes to sheets,

   155 it does include certain mechanisms for telling user agents about the intended

   156 page sheet <a href="#page-size">size and orientation</a>. In the general case,

   157 CSS3 assumes that one page box will be transferred to one surface of similar

   158 size.</p>

   160 <p>All properties defined in this specification also accept the

   161 <a href="http://www.w3.org/TR/CSS21/cascade.html#value-def-inherit">inherit</a>

   162 keyword as their value, but for readability it has not been listed explicitly.

   164 <h2 id="conformance">Conformance</h2>

   166 <p>All of the text in this specification is normative except sections

   167 explicitly marked as non-normative, examples, and notes. The keywords

   168 "<em class="RFC2119">MUST</em>", "<em class="RFC2119">SHALL</em>",

   169 "<em class="RFC2119">MUST NOT</em>", "<em class="RFC2119">SHALL NOT</em>",

   170 "<em class="RFC2119">REQUIRED</em>", "<em class="RFC2119">SHOULD</em>",

   171 "<em class="RFC2119">SHOULD NOT</em>", "<em class="RFC2119">RECOMMENDED</em>",

   172 "<em class="RFC2119">MAY</em>", and "<em class="RFC2119">OPTIONAL</em>" when

   173 used in this document are to be interpreted as described in <cite>RFC

   174 2119</cite> [[!RFC2119]]. However, for readability, these words do not appear

   175 in all uppercase letters in this specification.</p>

   177 <p>Examples in this specification are introduced with the words "for example"

   178   or are set apart from the normative text with <code>class="example"</code>,

   179   like this:

   181 <div class="example">

   182   <p>This is an example of an informative example.</p>

   183 </div>

   185 <p>Informative notes begin with the word "Note" and are set apart from the

   186   normative text with <code>class="note"</code>, like this:

   188 <p class="note">Note, this is an informative note.</p>

   190 <h2 id="page-terms">Page Terminology</h2>

   192 <p>The following terminology and accompanying diagrams help to describe the

   193 page model:</p>

   195 <dl>

   196   <dt id="page-sheet">Page sheet</dt>

   197   <dd><img src="PageSheet.png" style="float: right;" alt="The corner of a page sheet with the non-printable area at the edge and printable area inside it"

   198   height="148" width="194">The page sheet is one surface of the physical

   199   medium. The illustration to the right shows a representation of the upper-left

   200   corner of a page sheet.</dd>

   202   <dt id="printable-area">Printable and non-printable areas</dt>

   203   <dd>The non-printable area is the area of a page sheet that a physical device such

   204   as a printer is not capable of marking reliably, usually due to the printer's

   205   paper handling mechanism. This value is printer dependent and is usually a

   206   small region along each edge of the page sheet. The printable area is the area

   207   of page sheet that a printer <em>is</em> capable of marking reliably. The size

   208   of the printable area is the size of the page sheet reduced by the size of the

   209   non-printable area. A user agent may not know the dimensions of this area for a

   210   particular printing device; but when its dimensions are known, user agents

   211   <em class="RFC2119">MAY</em> adjust the formatting of the document so that

   212   content falls within the printable area. How this adjustment is accomplished is

   213   device dependent within the constraints expressed in the sections

   214   <a href="#renderingpages">Rendering page boxes that do not fit a page sheet</a> and

   215   <a href="#content-outside-box">Content outside the page box</a>.</dd>

   217   <dt id="page-orientation">Page Orientation</dt>

   218   <dd>The page orientation is defined by comparing the length of the edges of a

   219   <a href="#page-box">page box</a>. The page box is a rectangle with two

   220   perpendicular edges called the long edge and the short edge. The length of the

   221   long edge is always greater than or equal to the length of the short edge. When

   222   the page box is square, the two edges are of the same length and either can be

   223   used as the long edge with the other being the short edge. This specification

   224   defines page orientations of 'portrait' and 'landscape'.</dd>

   226   <dt id="portrait">Portrait Orientation</dt>

   227   <dd>A portrait page's height is greater than or equal to its width. Horizontal

   228   elements are parallel to the short edge and vertical elements to the long edge.</dd>

   230   <dt id="landscape">Landscape Orientation</dt>

   231   <dd>A landscape page's width is greater than or equal to its height. Horizontal

   232   elements are parallel to the long edge and vertical elements to the short edge.

   233   <span class="note">Note that CSS3 makes no distinction between landscape and

   234   reverse-landscape orientations. However, future versions of CSS may do so.

   235   UAs should consider, when formatting for duplexed printing, the binding edge,

   236   page progression, and ease of reading when choosing between landscape and

   237   reverse-landscape renderings.</span>

   238   </dd>

   240   <dt id="duplex-printing">Duplex Printing</dt>

   241   <dd>Duplex printing prints one page box per side of a page sheet and uses both

   242   sides of the page sheet. This module provides no ability to specify whether a

   243   document is duplex printed, but the concept of left and right pages is based on

   244   the assumption that the document is duplex printed, regardless of whether or

   245   not it actually is.</dd>

   247   <dt id="binding-edge">Binding Edge</dt>

   248   <dd>The binding edge is the edge of the page box that is toward the binding if the

   249   material is bound. The binding edge often has a larger margin than the opposite

   250   edge to provide for the space used by the binding. The binding edge can be any

   251   of the four edges. However, page sheets are customarily bound so that the

   252   binding edge of page boxes with portrait orientation is vertical. This module

   253   provides no method to specify the binding edge. In duplex printing, the binding

   254   edge is on opposite sides of the page box for the left and right pages.</dd>

   256   <dt id="facing-pages">Facing Pages</dt>

   257   <dd>Facing pages are two sequential pages such that when the document is duplex

   258   printed they are on separate sheets of paper. Typically, the earlier page will

   259   be the back side of one sheet and the later page will be the front side of

   260   another. They are usually laid out so that the binding edges of facing pages

   261   are vertical and adjacent when the pages are placed in their normal reading

   262   orientation.</dd>

   264   <dt id="left-page">Left Page</dt>

   265   <dd>A page that would be on the left if it is part of a pair of facing pages as

   266   typically laid out. Page layouts for documents using a left-to-right page

   267   progression have the earlier of the facing pages on the left. Rules specific to

   268   the left page can be specified using the <span class="css">':left'</span> page

   269   selector.</dd>

   271   <dt id="right-page">Right Page</dt>

   272   <dd>A page that would be on the right if it is part of a pair of facing pages as

   273   typically laid out. Page layouts for documents using a right-to-left page

   274   progression have the earlier of the facing pages on the right. Rules specific

   275   to the right page can be specified using the <span class="css">':right'</span>

   276   page selector.</dd>

   277 </dl>

   280 <h2 id="page-box-page-rule">The Page Model</h2>

   282 <p>In the paged media formatting model, the document is transferred into one

   283 or more page boxes. The <dfn id="page-box">page box</dfn> is a specialized CSS

   284 box that maps to a rectangular print media surface, such as a page of paper.

   285 It is roughly analogous to the <a href="http://www.w3.org/TR/CSS21/visuren.html#viewport">viewport</a>.

   286 <img src="PageBox.png" style="float: right;" alt="" height="266" width="267">

   288 <p>As with other CSS <a href="http://www.w3.org/TR/CSS21/box.html">boxes</a>, a page box

   289 consists of margin, border, padding, and content areas. The content and

   290 margin areas of a page box have special functions:</p>

   292 <ul>

   293   <li>The content area of a page box is called the <dfn id="page-area">page

   294   area</dfn>. The content of the document is flowed into one or more page boxes.

   295   The page area acts as a container for all the boxes generated by the root

   296   element and its descendants that are laid out within a given page box. The

   297   edges of the page area on the first page establish the rectangle that is the

   298   initial <a href="http://www.w3.org/TR/CSS21/visudet.html#containing-block-details">containing block</a>

   299   of the document.</li>

   300   <li>The margin area of a page box is divided into

   301   16 <dfn>page-margin boxes</dfn>.

   302   Each page-margin box has its own margin, border, padding and content areas.

   303   Page-margin boxes are typically used to display running headers and footers.</li>

   304 </ul>

   306 <p>The properties of a <i>page box</i> are determined by properties

   307 <a href="http://www.w3.org/TR/CSS21/syndata.html#declaration">declared</a> within the

   308 <i>page context</i>, which is the

   309 <a href="http://www.w3.org/TR/CSS21/syndata.html#x14">declaration block</a> of the

   310 <code>@page</code> rule. Similarly the properties of a <i>page-margin box</i>

   311 are determined by properties declared within its <i>margin context</i>.

   312 Declarations in the page context can affect the page box and/or inherit

   313 to the page-margin boxes, but they do not apply to or inherit into the

   314 document's root element or other content.</p>

   316 <p>The <i>containing block</i> of the page box is specified using the 'size'

   317 property in the <i>page context</i>. The width and horizontal margins

   318 of the page box are then calculated exactly as for a

   319 <a href="http://www.w3.org/TR/CSS21/visudet.html#blockwidth">non-replaced

   320 block element in normal flow</a>. [[!CSS21]] The height and vertical margins

   321 of the page box are calculated analogously (instead of using the block height

   322 formulas). In both cases if the values are over-constrained, instead of

   323 ignoring any margins, the containing block is resized to coincide with the

   324 margin edges of the page box.

   326 <h3 id="painting">

   327 Page Backgrounds and Painting Order</h3>

   329   <p>When drawing a page of content, the page layers are painted in the

   330   following painting order (bottommost first):

   332   <ol>

   333     <li>page background

   334     <li>document canvas

   335     <li>page borders

   336     <li>document contents

   337     <li>page-margin boxes

   338   </ol>

   340   <p>In the page model, the page background behaves similar to the root background:

   341   its <a href="http://www.w3.org/TR/css3-background/#background-painting-area"><i>background painting area</i></a>

   342   is the entire page box, including its margins (regardless of 'background-clip').

   343   Page backgrounds are anchored within the page box's padding area by default

   344   (and honor 'background-origin' if the UA supports [[!CSS3BG]]).

   345   However if 'background-attachment' is ''fixed''

   346   then the image is positioned relative to the page box including its margins

   347   (i.e. the <a href="http://www.w3.org/TR/css3-background/#background-positioning-area"><i>background positioning area</i></a>,

   348   like the <i>background painting area</i>, is the page's margin box).

   350   <p>The document canvas background is drawn as the page box's background:

   351   by default its <i>background painting area</i> covers the page box's border box,

   352   and for UAs that support [[!CSS3BG]], follows the 'background-clip' value specified on the root element.

   353   It remains, however, positioned with respect to the root element

   354   or page area as usual.

   356   <p>The UA may support the <code>z-index</code> property for page-margin boxes.

   357   With respect to the page-margin boxes,

   358   the document canvas, page borders, and all of the document contents

   359   are treated as a single element with a <code>z-index</code> value of '0':

   360   the page-margin boxes never interleave with parts of the document content

   361   or between the content and the canvas.

   362   They may only paint in front of the document content or behind the document canvas.

   363   The page background is always painted underneath everything else.

   364   Since the <code>position</code> property does not apply to page-margin boxes,

   365   <code>z-index</code> always affects page-margin boxes

   366   as if they were positioned elements

   367   regardless of the <code>position</code> property's value.

   369   <p>The default painting order,

   370   or <a href="http://www.w3.org/TR/CSS21/zindex.html">CSS2.1 Appendix E</a> "tree order",

   371   of page-margin boxes with respect to each other is not specified.

   372   However, the page-margin boxes are defined to come

   373   after the page box and its contents.

   374   <span class="issue">Suggestions here are welcome.</span>

   376 <h3 id="content-outside-box">Content outside the page box</h3>

   378 <p>When formatting content in the page model, some content may end up outside the

   379 page box. For example, an element whose 'white-space' property has the value

   380 'pre' can generate a box that is wider than the page box. As another example,

   381 when boxes are positioned absolutely or relatively, they may end up in

   382 "inconvenient" locations. For example, images may be placed on the edge of

   383 the page box or 100,000 meters below the page box. </p>

   385 <p>A specification for the exact formatting of such elements lies outside the

   386 scope of this document. However, it is recommended that authors and user agents

   387 observe the following general principles concerning content outside the page

   388 box:</p>

   390 <ul>

   391   <li><p>Content should be allowed slightly beyond the page box to allow pages

   392   to "bleed".

   393   <li><p>User agents <em class="RFC2119">SHOULD</em> avoid generating a large

   394   number of content-empty pages to honor the positioning of elements (e.g.,

   395   printing 100 blank pages is probably neither the author's nor the user's

   396   intent).

   397   A <dfn id="content-empty">Content-empty page</dfn> is a page box whose page

   398   area contains no printable content other than backgrounds and/or borders. A

   399   page box whose page area contains generated content, or content whose

   400   visibility is 'hidden', or invisible content such as a zero-width space is

   401   not a content-empty page. On the other hand, a page containing only a

   402   background and/or borders and/or page-margin box content <em>is</em> a

   403   content-empty page.

   404   <p class="note">Note, however, that generating a small number of empty page

   405   boxes is sometimes necessary to honor the <span class="css">'left'</span> and

   406   <span class="css">'right'</span> values for <span class="property">'break-before'</span>

   407   and <span class="property">'break-after'</span>.</li>

   409   <li><p>Authors <em class="RFC2119">SHOULD NOT</em> position elements in

   410   inconvenient locations just to avoid rendering them. Instead:

   411   <ul>

   412     <li>To suppress box generation entirely, set the <span class="property">'display'</span> property to <span class="css">'none'</span>.</li>

   413     <li>To make a box invisible, set the <span class="property">'visibility'</span>

   414     property.</li>

   415     </ul></li>

   416     <li><p>This specification does not define how boxes positioned outside the page

   417     box are handled. Possibilities include discarding them or creating page boxes

   418     for them at the end of the document.</li>

   419 </ul>

   421 <h3 id="progression">Page Progression</h3>

   423 <p>CSS distinguishes between left pages and right pages on all documents,

   424 whether they are printed duplex or not. Each left page is followed by a

   425 right page and vice versa. Left and right pages can be styled differently

   426 with the <a href="#left-right-first"><code>:left</code> and <code>:right</code>

   427 pseudo-classes</a>.

   429 <p>Whether the first page of a document is a left page or a right page

   430 depends on the page progression of the document. The <dfn>page progression</dfn>

   431 is the direction in which the printed pages of a document would be sequenced

   432 when laid out side-to-side. For example, English and horizontally-set Japanese

   433 typically progress from left to right, whereas Arabic and vertically-set

   434 Japanese pages typically progress from right to left. In documents with

   435 a left-to-right page progression the first page of the document is a right

   436 page, and vice versa.</p>

   438 <p>The page progression direction is determined as follows:</p>

   440 <ul>

   441   <li>If text is laid out in horizontal lines, the page progression is the

   442   same as the inline progression.</li>

   443   <li>If text is laid out in vertical lines, the page progression is the

   444   same as the block progression.</li>

   445 </ul>

   447 <p>If the UA supports the 'direction' and 'writing-mode' properties

   448 from the CSS 3 Writing Modes Module [[CSS3-WRITING-MODES]], it must

   449 <a href="http://www.w3.org/TR/css3-writing-modes/#page-direction">determine</a>

   450 whether the first page is a left or right page from the values of those

   451 properties on the root element.</p>

   453 <p>

   454   To explicitly force a document to begin printing on a left or right page,

   455   authors can specify a <a href="http://www.w3.org/TR/css3-break/#break-before">'break-before'</a> value

   456   that that propagates a page break to the root. [[!CSS3-BREAK]]

   457   The UA must suppress the first (empty) page(s) in this case

   458   (and the <code>:first</code> selector applies to the first printed page).

   460 <div class="example">

   461 <pre>

   462 html { break-before: always }

   463 </pre>

   465 <p>

   466   For an HTML document with a left-to-right page progression,

   467   the above style rule will cause the first page of the document

   468   to print on a ':left' page

   469 </p>

   471 <pre>

   472 html { break-before: left }

   473 </pre>

   475 <p>

   476   For an HTML document,

   477   the above style rule will cause the first page of the document

   478   to print on a ':left' page,

   479   regardless of the page progression.

   480 </p>

   481 </div>

   483 <h2 id="page-selector-and-context">Page Selectors and the Page Context</h2>

   485 <h3 id="at-page-rule">The @page Rule</h3>

   487 <p>Authors can specify various aspects of a page box, such as its dimensions,

   488 orientation, and margins, within an <span class="css">@page</span> rule.

   489 ''@page'' rules are allowed at the top-level of a stylesheet,

   490 as well as wherever

   491 <a href="http://www.w3.org/TR/CSS21/syndata.html#rule-sets">rule-sets</a>

   492 are allowed.

   493 An <span class="css">@page</span> rule consists of

   494 the keyword <span class="css">'@page'</span>,

   495 an <em class="RFC2119">OPTIONAL</em> comma-separated list of

   496 <i title="page selector">page selectors</i>

   497 and a block of declarations

   498 (said to be in the <dfn id="page-context">page context</dfn>).

   499 An ''@page'' rule can also contain other at-rules,

   500 interleaved between declarations.

   501 The current level of this specification

   502 only allows <a href="#margin-at-rules">margin at-rules</a> inside ''@page''.

   504 <p>A <dfn id="page-selector">page selector</dfn> is either

   505 one or more page pseudo-classes,

   506 or a page name followed by zero or more page pseudo-classes.

   507 No whitespace is allowed between a page name and a page pseudo-class,

   508 or between two pseudo-classes.

   509 The page selector specifies for which pages the declarations apply.

   510 In CSS3, page selectors can designate the first page of a document,

   511 all left pages, all right pages, or

   512 <a href="#using-named-pages">pages with specific names</a>.

   514 <p>If a <i>page selector</i> has multiple pseudo-classes,

   515 only pages that match all of the pseudo-classes match the selector.

   516 Multiple selectors may be combined with a comma (which may be preceded and/or

   517 followed by white space); in this case the ''@page'' rule applies to pages

   518 that match any of the page selectors.

   519 If no page selector is given, then the ''@page'' rule applies to all pages.</p>

   521 <p>Properties declared within the page context apply to the page box.</p>

   523 <p>If an error is encountered during the processing of a declaration block within

   524 a page or a margin context, the <a href="http://www.w3.org/TR/CSS21/syndata.html#parsing-errors">Rules for handling parsing errors</a>

   525 apply; that is, valid declarations within the block are applied.</p>

   527 <h3 id="pseudo-classes">

   528   <a id="left-right-first"></a>

   529   Page pseudo-classes: :left, :right, :first, and :blank

   530 </h3>

   532 <p>

   533   When printing double-sided documents,

   534   left and right pages are often formatted differently.

   535   This can be expressed through CSS pseudo-classes defined

   536   in the <a href="#page-context">page context</a>.

   537 </p>

   539 <p>

   540   All pages are automatically classified by user agents

   541   as either left pages or right pages,

   542   based on <a href="#progression">page progression</a>.

   543   The <span class="css">':left'</span> and <span class="css">':right'</span>

   544   page pseudo-classes can be used to selectively apply rules

   545   to only the left or right pages, respectively.

   546 </p>

   548 <div class="example">

   549 The following example creates left and right binding edges using these pseudo-classes:

   550 <pre>

   551 @page :left {

   552 margin-left: 3cm;

   553 margin-right: 4cm;

   554 }

   556 @page :right {

   557 margin-left: 4cm;

   558 margin-right: 3cm;

   559 }

   560 </pre>

   561 </div>

   563 <p>If different declarations have been given for left and right pages, the user

   564 agent <em class="RFC2119">MUST</em> honor these declarations even if the user

   565 agent does not transfer the page boxes to left and right sheets (i.e., a

   566 printer that only prints on one side of the medium must nevertheless produce

   567 correctly formatted output).</p>

   569 <div class="note">

   570 <p>

   571   <em><strong>Note.</strong>

   572   Adding declarations to the <span class="css">':left'</span> or

   573   <span class="css">':right'</span> pseudo-class

   574   does not necessarily influence whether the document

   575   comes out of the printer double- or single-sided

   576   (which is outside the scope of this specification).</em>

   577 </p>

   578 </div>

   580 <p>Authors can also specify style for the first page of a document with the

   581 <span class="css">':first'</span> pseudo-class. Such style rules are applied only

   582 to the first printed page of a document.</p>

   584 <div class="example">

   585 <pre>

   586 @page { margin: 2cm } /* All margins set to 2cm */

   588 @page :first {

   589 margin-top: 10cm /* Top margin on first page 10cm */

   590 }

   591 </pre>

   592 </div>

   594 <p>

   595   <i title="content-empty page">Content-empty pages</i>

   596   that appear as a result of

   597   <a href="http://www.w3.org/TR/css3-break/#forced-breaks">forced page breaks</a>

   598   can be styled with the <code>:blank</code> pseudo-class.

   600 <div class="note">

   601   <p>Only the ''left'', ''right'', ''recto'' and ''verso'' values

   602     of the 'break-before' and 'break-after' properties

   603     can generate pages that match '':blank''.

   604 </div>

   606 <div class="example">

   607 <p>In this example, forced page break may occur before <code>h1</code> elements.

   608 <pre>

   609 h1 { break-before: left }

   611 @page :blank {

   612   @top-center { content: "This page is intentionally left blank" }

   613 }

   614 </pre>

   615 </div>

   617 <p>

   618   A page matched by <code>:blank</code> can also be matched

   619   by other page pseudo-classes.

   621 <div class="example">

   623 <p>If headers have been specified on all right pages, a blank right

   624 page will be matched by both <code>:blank</code>

   625 and <code>:right</code>. Therefore, margin boxes set on right pages

   626 will have to be removed unless they are wanted on blank pages. Here is

   627 an example where the top center header is removed from blank pages,

   628 while the page number remains:

   630 <pre>

   631 h1 { break-before: left }

   633 @page :blank {

   634   @top-center { content: none }

   635 }

   637 @page :right {

   638   @top-center { content: "Preliminary edition" }

   639   @bottom-center { content: counter(page) }

   640 }

   641 </pre>

   643 <p>Due to the higher specificity of <code>:blank</code>

   644 over <code>:right</code>, the top center header is removed even

   645 if <code>content: none</code> comes before <code>content: "Preliminary

   646 edition"</code>.

   648 </div>

   650 <div class="note">

   651 <p><em><strong>Note.</strong> Future versions of CSS may include other page

   652 pseudo-classes.</em></p>

   653 </div>

   655 <h3 id="syntax-page-selector">@page rule grammar</h3>

   657 <p>The syntax for the @page rule is a specialization of the generic at-rule

   658 defined by CSS 2.1. This grammar extends the at-rule syntax to allow @page rules

   659 nested inside @media rules. User agents <em class="RFC2119">MUST</em> adhere

   660 to the following grammar:</p>

   662 <p>See [[!CSS21]], Section 4.1.1 and Appendix G for the expansion of missing

   663 productions:</p>

   664 <p id="specializatons-of-ATKEYWORD">

   665 All new lexical tokens are specializations of the ATKEYWORD lexical token:</p>

   666 <pre class="lexical">

   667 PAGE_SYM              ::= "@page"

   668 TOPLEFTCORNER_SYM     ::= "@top-left-corner"

   669 TOPLEFT_SYM           ::= "@top-left"

   670 TOPCENTER_SYM         ::= "@top-center"

   671 TOPRIGHT_SYM          ::= "@top-right"

   672 TOPRIGHTCORNER_SYM    ::= "@top-right-corner"

   673 BOTTOMLEFTCORNER_SYM  ::= "@bottom-left-corner"

   674 BOTTOMLEFT_SYM        ::= "@bottom-left"

   675 BOTTOMCENTER_SYM      ::= "@bottom-center"

   676 BOTTOMRIGHT_SYM       ::= "@bottom-right"

   677 BOTTOMRIGHTCORNER_SYM ::= "@bottom-right-corner"

   678 LEFTTOP_SYM           ::= "@left-top"

   679 LEFTMIDDLE_SYM        ::= "@left-middle"

   680 LEFTBOTTOM_SYM        ::= "@left-bottom"

   681 RIGHTTOP_SYM          ::= "@right-top"

   682 RIGHTMIDDLE_SYM       ::= "@right-middle"

   683 RIGHTBOTTOM_SYM       ::= "@right-bottom"

   685 <span id="syntax-prod-media">media</span> :

   686      MEDIA_SYM S* medium [ COMMA S* medium ]* LBRACE S* [ page | ruleset ]* '}' S*

   687      ;

   689 <span id="syntax-prod-page" title="">page</span> :

   690      PAGE_SYM S* [ page_selector S* [ ',' page_selector S* ]* ]?

   691      '{' S* page_body '}' S*

   692      ;

   694 <span id="syntax-prod-page-body">page_body</span> :  /* Can be empty */

   695      declaration? [ ';' S* page_body ]? |

   696      page_margin_box page_body

   697      ;

   699 <span id="syntax-prod-page-selector">page_selector</span> :

   700      pseudo_page+ | IDENT pseudo_page*

   701      ;

   702 <span id="syntax-prod-pseudo-page">pseudo_page</span> :

   703      ':' [ "left" | "right" | "first" | "blank" ]

   704      ;

   706 <span id="syntax-prod-margin">page_margin_box</span> :

   707      margin_sym S* '{' S* declaration? [ ';' S* declaration? ]* '}' S*

   708      ;

   710 <span id="syntax-prod-margin-sym">margin_sym</span> :

   711      TOPLEFTCORNER_SYM |

   712      TOPLEFT_SYM |

   713      TOPCENTER_SYM |

   714      TOPRIGHT_SYM |

   715      TOPRIGHTCORNER_SYM |

   716      BOTTOMLEFTCORNER_SYM |

   717      BOTTOMLEFT_SYM |

   718      BOTTOMCENTER_SYM |

   719      BOTTOMRIGHT_SYM |

   720      BOTTOMRIGHTCORNER_SYM |

   721      LEFTTOP_SYM |

   722      LEFTMIDDLE_SYM |

   723      LEFTBOTTOM_SYM |

   724      RIGHTTOP_SYM |

   725      RIGHTMIDDLE_SYM |

   726      RIGHTBOTTOM_SYM

   727      ;

   728 </pre>

   730 <p id="page-selector-syntax-restrict">

   731 The value 'auto' is not a valid page name and must be treated as matching

   732 nothing.

   734 <div class="example">

   736 <p>The following are examples of page selectors (declaration block intentionally

   737 left blank)</p>

   738 <pre>

   739 @page { ... }

   740 @page :left { ... }

   741 @page :right { ... }

   742 @page LandscapeTable { ... }

   743 @page CompanyLetterHead:first { ... } /*  identifier and pseudo page. */

   744 @page:first { ... };

   745 </pre>

   747 <p>The following are examples of page-margin boxes

   748 where the declaration blocks are intentionally left blank.</p>

   749 <pre>

   750 @page {

   751  @top-left { ... /* document name */ }

   752  @bottom-center { ... /* page number */}

   753 }

   754 @page :left { @left-middle { ... /* page number in left margin */ }}

   755 @page :right{ @right-middle { ... /* page number in right margins of right pages */}}

   757 @page :left { @bottom-left-corner { ... /* left page numbers */ }}

   758 @page :right { @bottom-right-corner { ... /* right page numbers */ }}

   759 @page :first { @bottom-left-corner { ... /* empty footer on 1st page */ }

   760              @bottom-right-corner { ... /* empty footer */ } }

   761 </pre>

   762 </div>

   764 <h3 id="cascading-and-page-context">Cascading in the page context</h3>

   766 <p>Declarations in page and margin contexts <a href="http://www.w3.org/TR/CSS21/cascade.html">cascade</a> just like declarations in <a href="http://www.w3.org/TR/CSS21/syndata.html#rule-sets">rule sets</a>.</p>

   768 <p>The specificity of page selectors is computed in a manner analogous to the

   769 computations defined in the <a href="http://www.w3.org/TR/CSS21/selector.html">Selectors</a>

   770 module:</p>

   772 <p>Each comma-separated selectors in the same ''@page'' rule

   773   match pages with its own specificity.

   774   ''@page'' rules without selectors are considered to have a single,

   775   empty selector (whose specificity is zero.)

   777 <ul>

   778   <li>Count the number of page names (= <var>f</var>)

   779     <p class="note">This is 0 or 1.

   780   <li>Count the number of ':first' or ':blank' pseudo-classes (= <var>g</var>)

   781   <li>Count the number of ':left' or ':right' pseudo-classes (= <var>h</var>)

   782 </ul>

   784 <p>

   785  Specificities are compared by comparing the three components in order:

   786  the specificity with <var>f</var> larger a value is more specific;

   787  if the two <var>f</var> values are tied,

   788  then the specificity with a larger <var>g</var> value is more specific;

   789  if the two <var>g</var> values are also tied,

   790  then the specificity with a larger <var>h</var> value is more specific;

   791  if all the values are tied, the two specifities are equal.

   793 <p>

   794   Due to storage limitations,

   795   implementations may have limitations on

   796   the size of <var>f</var>, <var>g</var>, or <var>h</var>.

   797   If so, values higher than the limit must be clamped to that limit,

   798   and not overflow.

   800 <p class="note">

   801 Note: Repeated occurrances of the same pseudo-classes are allowed

   802   and do increase specificity.

   804 <div class="example">

   806 <p>Some page specificity calculation examples follow:</p>

   807 <pre>

   808 @page { } /* specificity = (0,0,0) */

   809 @page :left { } /* specificity = (0,0,1) */

   810 @page :first { } /* specificity = (0,1,0) */

   811 @page artsy { } /* specificity = (1,0,0) */

   812 @page artsy:left { } /* specificity = (1,0,1) */

   813 @page artsy:first { } /* specificity = (1,1,0) */

   814 </pre>

   815 </div>

   817 <div class="example">

   819 <p>Consider the following usage example:</p>

   820 <pre>

   821 @page {

   822   margin-left: 3cm;

   823 }

   825 @page :left {

   826   margin-left: 4cm;

   827 }

   828 </pre>

   830 <p>Due to the higher specificity of the pseudo-class selector,

   831 the left margin on left pages will be 4cm and all other pages

   832 (the right-facing pages) will have a left margin of 3cm.

   833 </div>

   835 <div class="example">

   836 <p>In this example, the higher specificity of the green rules wins over the red

   837 rule.

   838 Therefore the first page will have blue text in the top-left page-margin box

   839 and green text in the top-right page-margin box,

   840 while subsequent pages will have red text in the page-margin boxes.</p>

   841 <pre>

   842 @page :first {

   843   color: green;

   845   @top-left {

   846     content: "foo";

   847     color: blue;

   848   }

   849   @top-right {

   850     content: "bar";

   851   }

   852 }

   854 @page { color: red;

   855   @top-center {

   856     content: "Page " counter(page);

   857   }

   858 }

   859 </pre>

   860 </div>

   862 <div class="example">

   864 <p>Page contexts cascade, so the following stylesheet would style pages with 25

   865 millimeter margins and 14 point type in the page-margin boxes:</p>

   866 <pre>

   867 @page { margin: 25mm;}

   868 @page { font-size: 14pt;}

   869 </pre>

   870 </div>

   872 <h2 id="margin-boxes">Page-Margin Boxes</h2>

   874   <p>Page-margin boxes are boxes within the page margin that,

   875   like pseudo-elements, can contain generated content.

   877   <p>Page-margin boxes can be used to create page headers and footers,

   878   which are portions of the page set aside for supplementary information

   879   such as the page number or document title.

   881   <div class="example">

   882     <p>Typically, a <dfn>page header</dfn> is located at the top of the page

   883     in documents with a predominately horizontal writing direction

   884     and on the side opposite the <a href="#binding-edge">binding edge</a>

   885     for documents with a predominately vertical writing direction.

   886     One possible design of page headers for horizontally written documents uses the

   887     ''@top-left-corner'', ''@top-left'', ''@top-center'', ''@top-right'' and ''@top-right-corner''

   888     page-margin boxes.

   889     Another design, for vertically written documents, could use the

   890     ''@right-top'', ''@right-middle'', and ''@right-bottom'' page-margin boxes

   891     for <a href="#right-page">right facing pages</a> and

   892     ''@left-top'', ''@left-middle'', and ''@left-bottom''

   893     for <a href="#left-page">left facing pages</a>.

   895     <p>The <dfn>page footer</dfn> is typically at

   896     the opposite end of the page from the page header.

   897     For example, the design of a horizontally written document with a page header

   898     at the top of the page could use the

   899     ''@bottom-left-corner'', ''@bottom-left'', ''@bottom-center'', ''@bottom-right'' and ''@bottom-right-corner''

   900     page-margin boxes as the page footer.

   901     The design of a vertically written document could use

   902     the page-margin boxes of the binding edge of the page for the page footer.

   903   </div>

   905   <p>Page-margin boxes are positioned with respect to the page area

   906   and are independent of page orientation,

   907   for example the top page-margin boxes are above the page area

   908   in both portrait and landscape orientation.

   909   The various page-margin boxes are defined

   910   and illustrated in the diagram below:

   912   <table id="margin-box-def" class="data" summary="defintion of each of the page-margin boxes">

   913     <caption>Table 1 Page-Margin Box Definitions</caption>

   914     <thead>

   915       <tr>

   916         <th>Box</th>

   917         <th>Description</th>

   918         <th>Placement</th>

   919       </tr>

   920     </thead>

   921     <tbody>

   922       <tr id="top-margin-boxes-def">

   923         <th id="top-left-corner-box-def">top-left-corner</th>

   924         <td>a fixed-size box defined by the intersection of the top and left margins of the

   925         page box</td>

   926         <td><img src="TopLeftCornerBox.png" alt="the top left corner box with margin, border, and padding, nested within intersection of the page's top and left margins"

   927         height="47" width="181"></td>

   928       </tr>

   929       <tr id="top-left-box-def">

   930         <th>top-left</th>

   931         <td>a variable-width box filling the top page margin between the top-left-corner

   932         and top-center page-margin boxes</td>

   933         <td><img src="TopLeftMarginBox.png" alt="the top left box with margin, border, and padding, nested in the page's top margin next to the top left corner box"

   934         height="47" width="181"></td>

   935       </tr>

   936       <tr id="top-center-box-def">

   937         <th>top-center</th>

   938         <td>a variable-width box centered horizontally between the page's left and right

   939         border edges and filling the page top margin between the top-left and top-right

   940         page-margin boxes</td>

   941         <td><img src="TopCenterMarginBox.png" alt="the top center box with margin, border, and padding, centered within the page's top margin"

   942         height="47" width="181"></td>

   943       </tr>

   944       <tr id="top-right-box-def">

   945         <th>top-right</th>

   946         <td>a variable-width box filling the top page margin between the top-center and

   947         top-right-corner page-margin boxes</td>

   948         <td><img src="TopRightMarginBox.png" alt="the top right box with margin, border, and padding, nested within the page's top margin"

   949         height="47" width="181"></td>

   950       </tr>

   951       <tr>

   952         <th id="top-right-corner-box-def">top-right-corner</th>

   953         <td>a fixed-size box defined by the intersection of the top and right margins of

   954         the page box</td>

   955         <td><img src="TopRightCornerMarginBox.png" alt="the top right corner box with margin, border, and padding, nested within the intersection of the page's top and right margin"

   956         height="47" width="181"></td>

   957       </tr>

   958       <tr id="left-margin-boxes-def">

   959         <th id="left-top-box-def">left-top</th>

   960         <td>a variable-height box filling the left page margin between the top-left-corner

   961         and left-middle page-margin boxes</td>

   962         <td rowspan="3"><img src="LeftMarginBoxes.png" alt="left-top, left-middle, and left-bottom page-margin boxes in the page box's left margin"

   963         height="226" width="181"></td>

   964       </tr>

   965       <tr id="left-middle-box-def">

   966         <th>left-middle</th>

   967         <td>a variable-height box centered vertically between the page's top and bottom

   968         border edges and filling the left page margin between the left-top and

   969         left-bottom page-margin boxes</td>

   970       </tr>

   971       <tr id="left-bottom-box-def">

   972         <th>left-bottom</th>

   973         <td>a variable-height box filling the left page margin between the left-middle and

   974         bottom-left-corner page-margin boxes</td>

   975       </tr>

   976       <tr id="right-margin-boxes-def">

   977         <th id="right-top-box-def">right-top</th>

   978         <td>a variable-height box filling the right page margin between the

   979         top-right-corner and right-middle page-margin boxes</td>

   980         <td rowspan="3"><img src="RightMarginBoxes.png" alt="right-top, right-middle, and right-bottom page-margin boxes in the page box's right margin"

   981         height="226" width="181"></td>

   982       </tr>

   983       <tr id="right-middle-box-def">

   984         <th>right-middle</th>

   985         <td>a variable-height box centered vertically between the page's top and bottom

   986         border edges and filling the right page margin between the right-top and

   987         right-bottom page-margin boxes</td>

   988       </tr>

   989       <tr id="right-bottom-box-def">

   990         <th>right-bottom</th>

   991         <td>a variable-height box filling the right page margin between the right-middle

   992         and bottom-right-corner page-margin boxes</td>

   993       </tr>

   994       <tr id="bottom-margin-boxes-def">

   995         <th id="bottom-left-corner-box-def">bottom-left-corner</th>

   996         <td>a fixed-size box defined by the intersection of the bottom and left margins of

   997         the page box</td>

   998         <td><img src="BottomLeftCornerBox.png" alt="bottom left corner box with margin, border, and padding, nested within the page margin at the intersection of the left and bottom page margins"

   999         height="48" width="181"></td>

  1000       </tr>

  1001       <tr id="bottom-left-box-def">

  1002         <th>bottom-left</th>

  1003         <td>a variable-width box filling the bottom page margin between the

  1004         bottom-left-corner and bottom-center page-margin boxes</td>

  1005         <td><img src="BottomLeftMarginBox.png" alt="bottom left page-margin box with margin, border, and padding, nested within the page's bottom margin next to the bottom-left-corner box"

  1006         height="48" width="181"></td>

  1007       </tr>

  1008       <tr id="bottom-center-box-def">

  1009         <th>bottom-center</th>

  1010         <td>a variable-width box centered horizontally between the page's left and right

  1011         border edges and filling the bottom page margin between the bottom-left and

  1012         bottom-right page-margin boxes</td>

  1013         <td style="vertical-align: middle;"><img src="BottomCenterMarginBox.png" alt="bottom center box with margin, border, and padding, nested within the page's bottom margin and centered on the page"

  1014         height="48" width="181"></td>

  1015       </tr>

  1016       <tr id="bottom-right-box-def">

  1017         <th>bottom-right</th>

  1018         <td>a variable-width box filling the bottom page margin between the bottom-center

  1019         and bottom-right-corner page-margin boxes</td>

  1020         <td><img src="BottomRightMarginBox.png" alt="bottom right page-margin box with margin, border, and padding, nested within the page's bottom margin and next to the bottom-right-corner box"

  1021         height="48" width="181"></td>

  1022       </tr>

  1023       <tr id="bottom-right-corner-box-def">

  1024         <th>bottom-right-corner</th>

  1025         <td>a fixed-size box defined by the intersection of the bottom and right margins of

  1026         the page box</td>

  1027         <td><img src="BottomRightCornerBox.png" alt="bottom right corner box with margin, border, and padding, nested within the page margin at the intersection of the right and bottom page margins"

  1028         height="48" width="181"></td>

  1029       </tr>

  1030     </tbody>

  1031   </table>

  1033 <h3 id="margin-at-rules">At-rules for page-margin boxes</h3>

  1035 <p>Page-margin boxes are created by

  1036 <a href="#margin-at-rules">margin at-rules</a>

  1037 inside the <a href="#page-context">page context</a>.

  1038 These rules should come after any declarations in the page context as legacy

  1039 clients may not handle declarations after margin at-rules correctly.</p>

  1041 <p>A <dfn id="margin-at-rule">margin at-rule</dfn> consists of an

  1042 <a href="#specializatons-of-ATKEYWORD">ATKEYWORD</a>

  1043 that identifies the page-margin box

  1044 (e.g. <span class="css">'@top-left'</span>) and a block of declarations (said

  1045 to be in the <dfn id="margin-context">margin context</dfn>).</p>

  1047 <div class="example">

  1049 <p>The following style sheet establishes a page header containing the title

  1050 ("Hamlet") on the left side and the page number, preceded by "Page ", on the

  1051 right side:</p>

  1052 <pre>

  1053 @page {

  1054   size: 8.5in 11in;

  1055   margin: 10%;

  1057   @top-left {

  1058     content: "Hamlet";

  1059   }

  1060   @top-right {

  1061     content: "Page " counter(page);

  1062   }

  1063 }

  1064 </pre>

  1065 </div>

  1068 <h3 id="populating-margin-boxes">Populating page-margin boxes</h3>

  1070 <p>As with the '':before'' and '':after'' pseudo-elements,

  1071 a specified 'content' of ''normal'' on a page-margin box computes to ''none'',

  1072 and the page-margin box is <dfn>generated</dfn>

  1073 if and only if the computed value

  1074 of its 'content' property is not 'none'.

  1075 Otherwise it behaves as if it had ''display: none''.

  1077 <div class="example">

  1078 <p>The following style sheet creates a green box in each corner of the page

  1079 except the bottom-left corner.</p>

  1080 <pre>

  1081   @page {

  1082     @top-left-corner { content: " "; border: solid green; }

  1083     @top-right-corner { content: url(foo.png); border: solid green; }

  1084     @bottom-right-corner { content: counter(page); border: solid green; }

  1085     @bottom-left-corner { content: normal; border: solid green; }

  1086   }

  1087 </pre>

  1088 </div>

  1090 <h3 id="margin-dimension">Computing Page-margin Box Dimensions</h3>

  1092 <p>The width and height of each page-margin box is determined by the rules

  1093 below. These rules define the equivalent of CSS2.1 Sections 10.3 and

  1094 10.6 for page-margin boxes.</p>

  1096 <p>The rules for applying 'min-height', 'max-height', 'min-width', and

  1097 'max-width' [[!CSS21]] do apply to page-margin boxes and may imply

  1098 a recalculation of the width, height, and/or margins

  1099 if the dimensions resulting from the specified 'width' or 'height'

  1100 violate their constraints.

  1101 If the UA does not support the 'min-height' or 'min-width' properties

  1102 then it must behave as if 'min-height' and 'min-width' were always zero.

  1104 <h4 id="margin-box-terms"><a id="max-margin-dimension"></a>Page-Margin Box Layout Terminology</h4>

  1106   <p>In addition to the box model definitions in CSS2.1 [[!CSS21]],

  1107   and the sizing terms in CSS Intrinsic Sizing [[!CSS3-SIZING]],

  1108   the following terms are defined for use

  1109   in the subsequent page-margin box calculations:

  1111   <dl>

  1113     <dt><dfn>available width</dfn></dt>

  1114     <dd>The sum of the page’s

  1115       left border width, left padding, <a href="#page-box">page area</a> width,

  1116       right padding, and right border width.

  1117       In other words, it is the distance between

  1118       the <a href="#page-box">page box</a>’s left right border edges.

  1119       This quantity is used  when calculating dimensions

  1120       of the top and bottom page-margin boxes.

  1122     <dt><dfn>available height</dfn></dt>

  1123     <dd>The sum of the page’s

  1124       top border width, top padding, <a href="#page-box">page area</a> height,

  1125       bottom padding, and bottom border width.

  1126       In other words, it is the distance between

  1127       the <a href="#page-box">page box</a>’s top bottom border edges.

  1128       This quantity is used when calculating dimensions

  1129       of the left and right page-margin boxes.

  1131     <dt><dfn>outer width</dfn></dt>

  1132     <dd>The width of the

  1133       <a href="http://www.w3.org/TR/CSS21/box.html#outer-edge">outer edge</a>,

  1134       as defined in [[!CSS21]].

  1136     <dt><dfn>outer min width</dfn></dt>

  1137     <dd>Like the <i>outer width</i>, except that

  1138     <a href="http://www.w3.org/TR/css3-sizing/#min-content">''min-content''</a>

  1139     is used when the width is ''auto''.

  1141     <dt><dfn>outer max width</dfn></dt>

  1142     <dd>Like the <i>outer width</i>, except that

  1143     <a href="http://www.w3.org/TR/css3-sizing/#max-content">''max-content''</a>

  1144     is used when 'width' is ''auto''.

  1145   </dl>

  1147   <p>The <dfn>containing block</dfn> for a corner page-margin box is

  1148   the rectangle defined by the intersection of the two page margins meeting at that corner.

  1150   <p>For all other page-margin boxes,

  1151   the <dfn>containing block</dfn> is the rectangle

  1152   formed by the encapsulating page margin minus the containing blocks of the

  1153   adjacent corners' page-margin boxes.

  1154   This means that the size of this containing block is given

  1155   in one dimension by the used page margin and in the other dimension

  1156   by the <i>available width</i>

  1157   (for top and bottom page-margin boxes) or

  1158   <i>available height</i>

  1159   (for left and right page-margin boxes).</p>

  1161 <h4 id="variable-sizing">

  1162 Page-Margin Box Variable Dimension Computation Rules</h4>

  1164 <p>The following rules apply to 'top-left', 'top-center' and 'top-right'

  1165 page-margin boxes,

  1166 which are referred to as A, B, and C, respectively, in this section.</p>

  1168 <h5 id="variable-auto-margins">Margins</h5>

  1170 <p>If the 'margin-left' or 'margin-right' property of any of the three boxes

  1171 computes to ''auto'', the used value is zero.</p>

  1173 <h5 id="variable-auto-sizing">Resolving ''auto'' widths</h5>

  1175 <p>The following algorithm determines the used width of each box.

  1176 For this purpose, boxes that are not <i>generated</i>

  1177 are assumed to have a 'width' and an <i>outer width</i> of zero.

  1178 </p>

  1180 <p class="note">

  1181 Note: The high-level goals are (in order of priority) to center the middle

  1182 box (B) if it is generated, to minimize overflow and overlap, and to

  1183 distribute space proportionally to the amount of content.</p>

  1185   <p>If the middle box (B) is not <i>generated</i>,

  1186   distribute the <i>available width</i> to A and C as follows:

  1188   <ul>

  1189     <li>

  1190       If only one box has 'width: auto',

  1191       its used width is resolved so that

  1192       the sum of the <i>outer width</i>s equals <i>available width</i>.

  1193     </li>

  1195     <li id="flex-fit">

  1196       If A and C both have 'width: auto', distribute the space to each box as follows:

  1197       <ol>

  1198         <li>If the sum of the outer <i>max-content widths</i> is less than the <i>available width</i>,

  1199             call that difference the <i>flex space</i>.

  1200             Calculate each box's <i>flex factor</i> as proportional to

  1201             its outer <i>max-content width</i>,

  1202             and set its used outer width to:

  1203               <pre><i>max-content width</i> + <i>flex space</i> × <i>flex factor</i> ÷ ∑<i>flex factors</i></pre>

  1204         <li>Otherwise if the sum of the outer <i>min-content widths</i> is less than the <i>available width</i>,

  1205             call that difference the <i>flex space</i>

  1206             calculate each box's <i>flex factor</i> as proportional to

  1207             its <i>max-content</i> minus <i>min-content</i>,

  1208             and set its used outer width to:

  1209               <pre><i>min-content width</i> + <i>flex space</i> × <i>flex factor</i> ÷ ∑<i>flex factors</i></pre>

  1210         <li>Otherwise,

  1211             calculate its outer size as in the previous case,

  1212             but set each box's <i>flex factor</i> as proportional to

  1213             its outer <i>min-content width</i>.

  1214       </ol>

  1215       In each case, both <i>flex factors</i> are assumed to be ''1'' if their sum is equal to zero.

  1216     </li>

  1217   </ul>

  1219   <p>If the middle box (B) is <i>generated</i>,

  1220   determine the ''auto'' widths of A, B, and C as follows:

  1222   <ol>

  1223     <li>

  1224       First, resolve any ''auto'' width of the middle box (B):

  1225       Assume there are two boxes, B and AC,

  1226       where each of AC's dimensions is double the maximum of A and C.

  1227       (This preserves B's centering.)

  1228       Distribute the space to these two boxes (B and the imaginary AC)

  1229       as described for A and C <a href="#fit2">above</a>.

  1230     <li>

  1231       Then, resolve any ''auto'' widths of the side boxes (A and C)

  1232       by setting that box's outer width to

  1233       <pre>(<i>available width</i> &minus; <i>used outer size of B</i>) ÷ 2<pre>

  1234     </li>

  1235   </ol>

  1237 <h5 id="variable-minmax">Handling 'min-width' and 'max-width'</h5>

  1239 <p>

  1240   The 'min-width' and 'max-width' properties [[CSS21]] apply to page-margin

  1241   boxes in the variable dimension like on normal elements, except that the

  1242   three boxes on the same side are considered together.

  1243 </p>

  1245 <p>

  1246   More precisely:

  1247 </p>

  1249 <ol>

  1250   <li>

  1251     The tentative used widths are calculated

  1252     (without 'min-width' and 'max-width') following the rules under

  1253     <a href="#marginbox-variabledim-with">Resolving ''auto'' widths</a>

  1254     above.

  1255   </li>

  1256   <li>

  1257     If the tentative used width of any of the three boxes

  1258     is greater than 'max-width', the rules above are applied again,

  1259     but this time using the computed value of 'max-width'

  1260     as the computed value for 'width'.

  1261   </li>

  1262   <li>

  1263     If the resulting width of any of the three boxes

  1264     is smaller than 'min-width', the rules above are applied again,

  1265     but this time using the value of 'min-width'

  1266     as the computed value for 'width'.

  1267   </li>

  1268 </ol>

  1270 <h5 id="variable-position">Positioning</h5>

  1272 <p>

  1273   Once the dimensions of the boxes are determined,

  1274   they are positioned as follows:

  1275 </p>

  1277 <ul>

  1278   <li>The left outer edge of A is flush with the left edge of the

  1279       containing block</li>

  1280   <li>The outer area of B is centered in the containing block.</li>

  1281   <li>The right outer edge of C is flush with the right edge of the

  1282       containing block.</li>

  1283 </ul>

  1285 <h5 id="variable-mapping">Boxes on other sides</h5>

  1287 <p>The used values for 'bottom-left', 'bottom-center' and 'bottom-right'

  1288 page-margin boxes are established by the same rules as

  1289 for 'top-left', 'top-center', and 'top-right', respectively.</p>

  1291 <p>The used values for 'left-top', 'left-middle' and 'left-bottom' boxes are

  1292 established by the same rules, with "width" replaced by "height", "left" by

  1293 "top", "right" by "bottom" and "center" by "middle".</p>

  1295 <p>The used values for 'right-top', 'right-middle' and 'right-bottom'

  1296 page-margin boxes

  1297 are established by the same rules as for 'left-top', 'left-middle' and

  1298 'left-bottom', respectively.</p>

  1300 <h4 id="fixed-sizing">Page-Margin Box Fixed Dimension Computation Rules</h4>

  1302 <p>The rules below are used to calculate the used values of each

  1303 'top-left-corner', 'top-left', 'top-center', 'top-right', and

  1304 'top-right-corner' page-margin box's 'height', 'margin-top', and 'margin-bottom'

  1305 properties:</p>

  1307 <ol>

  1308   <li>The following constraint must hold among the used values of the margin

  1309   box's properties:

  1310   <p>'margin-top' + 'border-top-width' + 'padding-top' + 'height' +

  1311   'padding-bottom' + 'border-bottom-width' + 'margin-bottom' = top page margin

  1313   <li>If 'border-top-width' + 'padding-top' + 'height' (if it is not ''auto'')

  1314   + 'padding-bottom' + 'border-bottom-width', plus 'margin-top' and/or

  1315   'margin-bottom' if not ''auto'', is larger than the height of the top page

  1316   margin, then any ''auto'' values for 'margin-top' or 'margin-bottom' are, for

  1317   the following rules, treated as zero.

  1319   <li>If at this point all of 'height', 'margin-top', and 'margin-bottom'

  1320   have a computed value other than ''auto'', the values are said to be

  1321   "over-constrained". In this case, the specified value of 'margin-top' is

  1322   treated as 'auto'.

  1324   <li>If there is now exactly one value specified as 'auto', its used value

  1325   follows from the equality.

  1327   <li>If 'height' is set to 'auto', any other 'auto' values become '0' and

  1328   'height' follows from the resulting equality

  1330   <li>If both 'margin-top' and 'margin-bottom' are 'auto',

  1331   their used values are equal.

  1332   This vertically centers the page-margin box content

  1333   within the top page margin.

  1334 </ol>

  1336 <p>The same rules apply to the bottom page-margin boxes (bottom-left-corner,

  1337 bottom-left, bottom-center, bottom-right, and bottom-right-corner), except that

  1338 in the overconstrained case, the 'margin-bottom' is ignored rather than the

  1339 'margin-top'.</p>

  1341 <p>Analogous rules govern the properties for the left and right

  1342 page-margin boxes with respect to 'width'

  1343 (top-left-corner, left-top, left-middle, left-bottom, and

  1344 bottom-left-corner; top-right-corner, right-top, right-middle, right-bottom,

  1345 bottom-right-corner), with 'top' replaced by 'left', 'bottom' replaced by

  1346 'right', and 'height' replaced by 'width'.

  1347 In the overconstrained case for left (right) page-margin boxes,

  1348 the specified value of 'margin-left' ('margin-right') is ignored.</p>

  1350 <h3 id="margin-box-ex">Page-margin box examples</h3>

  1352 <p>The following is a collection of examples of page-margin box usage.</p>

  1354 <div class="example">

  1356 <p>Here is an example of a page with only a top-left header:</p>

  1357 <pre>

  1358 @page {

  1359 @top-left { content: "Header in Left Cell (top-left)" }

  1360 }

  1361 </pre>

  1363 <p>Because there are no contents defined for the top-center or the top-right

  1364 page-margin boxes, the extent of the top-left page-margin box

  1365 is allowed to cross the center of the page box.</p>

  1367 <p><img alt="Header Example 1" src="header-ex-1.png" height="177" width="737"></p>

  1368 </div>

  1370 <div class="example">

  1372 <p>The following is an example of a page with a centered header:</p>

  1373 <pre>

  1374 @page {

  1375 @top-center { content: "Header in Center Cell (top-center)" }

  1376 }

  1377 </pre>

  1379 <p><img alt="Header Example 2" src="header-ex-2.png" height="177" width="737"></p>

  1380 </div>

  1382 <div class="example">

  1384 <p>The following is an example of a page with a single header in the top-right

  1385 page-margin box:</p>

  1386 <pre>

  1387 @page {

  1388 @top-right { content: "Header in Right Cell (top-right)" }

  1389 }

  1390 </pre>

  1392 <p>Because the content of the center cell is empty, the extent of the top-right

  1393 page-margin box is allowed to cross the center of the page box.</p>

  1395 <p><img alt="Header Example 3" src="header-ex-3.png" height="177" width="737"></p>

  1396 </div>

  1398 <div class="example">

  1400 <p>The following is an example of a page with a top-center and a top-left header:</p>

  1401 <pre>

  1402 @page {

  1403 @top-left { content: "Left Cell (top-left)" }

  1404 @top-center { content: "Header in Center Cell (top-center)" }

  1405 }

  1406 </pre>

  1408 <p><img alt="Header Example 4" src="header-ex-4.png" height="177" width="737"></p>

  1409 </div>

  1411 <div class="example">

  1413 <p>The following is an example of a page with a top-center and a top-right header:</p>

  1414 <pre>

  1415 @page {

  1416 @top-center { content: "Header in Center Cell (top-center)" }

  1417 @top-right { content: "Right Cell (top-right)" }

  1418 }

  1419 </pre>

  1421 <p><img alt="Header Example 5" src="header-ex-5.png" height="177" width="737"></p>

  1422 </div>

  1424 <div class="example">

  1426 <p>The following is an example of a page with top-left and top-right headers:</p>

  1427 <pre>

  1428 @page {

  1429 @top-left { content: "Header in top-left with approx. "

  1430                    "twice as many words as right cell." }

  1431 @top-right { content: "Right cell (top-right)" }

  1432 }

  1433 </pre>

  1435 <p>Because there are no center cell contents, the extent of the top-left is

  1436 allowed to cross the center of the page box.</p>

  1438 <p><img alt="Header Example 6" src="header-ex-6.png" height="177" width="737"></p>

  1439 </div>

  1441 <h2 id="page-properties">Page Properties</h2>

  1442 <div>

  1444 <p>The following properties, when used in the <a href="#page-context">page

  1445 context</a>, apply to the page box:</p>

  1447 <ul>

  1448   <li><a href="http://www.w3.org/TR/CSS21/colors.html#background-properties">background properties</a></li>

  1449   <li><a href="http://www.w3.org/TR/CSS21/box.html#border-properties">border properties</a></li>

  1450   <li><a href="http://www.w3.org/TR/CSS21/colors.html#propdef-color">color</a></li>

  1451   <li><a href="http://www.w3.org/TR/CSS21/generate.html#counters">counter properties</a></li>

  1452   <li><a href="http://www.w3.org/TR/CSS21/visuren.html#direction">direction</a>

  1453   <li><a href="http://www.w3.org/TR/CSS21/fonts.html">font properties</a></li>

  1454   <li><a href="http://www.w3.org/TR/CSS21/visudet.html#line-height">line-height</a></li>

  1455   <li><a href="http://www.w3.org/TR/CSS21/box.html#margin-properties">margin properties</a></li>

  1456   <li><a href="http://www.w3.org/TR/CSS21/ui.html#dynamic-outlines">outline properties</a>

  1457   <li><a href="http://www.w3.org/TR/CSS21/box.html#padding-properties">padding properties</a></li>

  1458   <li><a href="http://www.w3.org/TR/CSS21/generate.html#quotes-specify">quotes</a>

  1459   <li><a href="#page-size">size</a></li>

  1460   <li><a href="http://www.w3.org/TR/CSS21/text.html">text properties</a></li>

  1461   <li><a href="http://www.w3.org/TR/CSS21/visufx.html#visibility">visibility</a></li>

  1462 </ul>

  1464 <p>The following properties, when used in a <a href="#margin-at-rule">margin

  1465 context</a>, apply to page-margin boxes and their content:</p>

  1467 <ul>

  1468   <li><a href="http://www.w3.org/TR/CSS21/colors.html#background-properties">background properties</a>

  1469   <li><a href="http://www.w3.org/TR/CSS21/box.html#border-properties">border properties</a>

  1470   <li><a href="http://www.w3.org/TR/CSS21/colors.html#propdef-color">color</a>

  1471   <li><a href="http://www.w3.org/TR/CSS21/generate.html#content">content</a>

  1472   <li><a href="http://www.w3.org/TR/CSS21/generate.html#counters">counter properties</a></li>

  1473   <li><a href="http://www.w3.org/TR/CSS21/fonts.html">font properties</a>

  1474   <li><a href="http://www.w3.org/TR/CSS21/visudet.html#the-height-property">height</a> <a href="http://www.w3.org/TR/CSS21/visudet.html#min-max-heights">properties</a>

  1475   <li><a href="http://www.w3.org/TR/CSS21/visudet.html#line-height">line-height</a>

  1476   <li><a href="http://www.w3.org/TR/CSS21/box.html#margin-properties">margin properties</a>

  1477   <li><a href="http://www.w3.org/TR/CSS21/ui.html#dynamic-outlines">outline properties</a>

  1478   <li><a href="http://www.w3.org/TR/CSS21/visufx.html#overflow">overflow</a>

  1479   <li><a href="http://www.w3.org/TR/CSS21/box.html#padding-properties">padding properties</a>

  1480   <li><a href="http://www.w3.org/TR/CSS21/generate.html#quotes-specify">quotes</a>

  1481   <li><a href="http://www.w3.org/TR/CSS21/text.html">text properties</a>

  1482   <li><a href="http://www.w3.org/TR/CSS21/visudet.html#line-height">vertical-align</a>

  1483   <li><a href="http://www.w3.org/TR/CSS21/visufx.html#visibility">visibility</a>

  1484   <li><a href="http://www.w3.org/TR/CSS21/visudet.html#the-width-property">width</a> <a href="http://www.w3.org/TR/CSS21/visudet.html#min-max-widths">properties</a>

  1485   <li><a href="http://www.w3.org/TR/CSS21/visuren.html#z-index">z-index</a>

  1486 </ul>

  1488 <p>A detailed list of properties that <em class="RFC2119">MUST</em> be supported

  1489 within page and margin contexts by a conforming implementation can be found in

  1490 <a href="#properties-list">Appendix A</a>.</p>

  1492 <p>Other properties defined by [[!CSS21]] do not apply in these contexts. Behavior

  1493 for properties not included in CSS 2.1 and not listed here or in Appendix A is

  1494 undefined.</p>

  1496 <p class="note">

  1497 Note: The intent of leaving other properties undefined is to allow the gradual

  1498 addition of appropriate CSS3 properties as they emerge, without having to

  1499 update this specification with each addition.</p>

  1501 <p><a href="http://www.w3.org/TR/CSS21/cascade.html#value-stages">As with

  1502 elements in the document</a>, both the page context and the margin context

  1503 have a computed value for every property, even if that property does not

  1504 apply to the page or page-margin box.</p>

  1506 <p>The normal rules for CSS properties apply with the following exceptions:</p>

  1508 <ul>

  1509   <li>page-margin boxes inherit from the page context.

  1510   The page context inherits from the root element.

  1511   However, since the previous revision of CSS Paged

  1512   Media Level 3 did not specify this point, an implementation that sets

  1513   inherited properties in the page context to their initial values (as for the

  1514   root element) is also conformant to CSS Paged Media Level 3. Note that this

  1515   exception will be removed in Level 4.

  1516   <li>Values in units of ''em'' and ''ex'' are interpreted relative to the font

  1517   associated with their context. When used on the 'font-size' property in the

  1518   margin context, they are relative to the font of the page context. When used

  1519   on the 'font-size' property in the page context, they are relative to the

  1520   'font-size' of the root element. However, since a previous revision of CSS

  1521   Paged Media Level 3 was ambiguous on this point, an implementation that

  1522   treats ''em'' and ''ex'' on 'font-size' as relative to the initial value is

  1523   also conformant to CSS Paged Media Level 3. Note that this exception will

  1524   be removed in Level 4.

  1525   <li>Percentage values on the margin and padding properties are relative to the

  1526   dimensions of the containing block. For right and left values, percentages are

  1527   relative to the width of the containing block; for top and bottom values,

  1528   percentages are relative to the height of the containing block.</li>

  1529   <li>The used values of 'width' and 'height' have special computation rules

  1530   for page boxes and page-margin boxes; see <a href="#page-size">Page Size</a>

  1531   and <a href="#margin-box-dimensions">Computing Page-Margin Box Dimensions</a>.

  1532   <li>The page background is positioned and painted

  1533     <a href="#painting">as described above</a>.

  1534   <li>The rules for counter scoping are modified <a href="page-based-counters">as

  1535   described below</a>.</li>

  1536   <li>

  1537     As on the '::before' and '::after' pseudo-elements,

  1538     the ''normal'' value of the 'content' property computes to ''none''

  1539     on page-margin boxes.

  1540   </li>

  1541   <li>On page-margin boxes, the 'vertical-align' property behaves

  1542   <a href="http://www.w3.org/TR/CSS21/tables.html#height-layout">as specified for table cells</a>.

  1543   It <em>always</em> performs alignment in the vertical dimension,

  1544   regardless of writing mode.

  1545 </ul>

  1547 <p>It is <em class="RFC2119">recommended</em> that user agents establish a default

  1548 page margin via the user agent stylesheet that includes any non-printable area.

  1549 It is further <em class="RFC2119">recommended</em> that authors assume that the

  1550 default page area will not include unprintable regions.</p>

  1552 <h3 id="page-based-counters">Page-based counters</h3>

  1554 <p>Counters can be defined and controlled within an <span class="css">'@page'</span>

  1555 rule, and used as content in page-margin boxes.

  1556 This is useful for maintaining a page count.</p>

  1558 <p>A 'counter-increment' within either a page or margin context causes the counter

  1559 to increment with the generation of each page box.</p>

  1561 <p>If a counter is reset or incremented within the page context, it is in scope

  1562 for all page-margin boxes and obscures all counters of the same name within the

  1563 document.</p>

  1565 <p>If a counter is reset or incremented within a margin context, it is in scope

  1566 for that page-margin box and obscures any counters of the same name

  1567 in both the page context and the document.</p>

  1569 <p>If a counter that has not been reset or incremented within the margin context

  1570 or the page context is used by counter() or counters() in the margin context,

  1571 then the resultant value is exactly

  1572 as if the page-margin box were an element within

  1573 the document at the start of the page, inside the deepest element in the normal

  1574 flow that spans the page break. Use of the counter in this way does not affect

  1575 the calculation of the counter's value.</p>

  1577 <p>

  1578   A counter named ''page'' is automatically created

  1579   and incremented by 1 on every page of the document,

  1580   unless the 'counter-increment' property in the <i>page context</i>

  1581   explicitly specifies a different increment for the ''page'' counter.

  1582   The implied ''page'' counter is a real counter,

  1583   and can be directly affected using the 'counter-increment' and 'counter-reset' properties

  1584   when named explicitly in those properties.

  1585   It can also be used in the 'counter()' and 'counters()' function forms.

  1586 </p>

  1588 <div class="example">

  1589 <p>The following rules result in the placement of the current page number in the

  1590 middle of the outside margin of each page.</p>

  1591 <pre>

  1592 @page {

  1593   margin: 10%;

  1595   @top-center {

  1596     font-family: sans-serif;

  1597     font-weight: bold;

  1598     font-size: 2em;

  1599     content: counter(page);

  1600   }

  1601 }

  1602 </pre>

  1604 <p>Adding the following rule will make all pages even-numbered.</p>

  1605 <pre>

  1606 @page {

  1607   counter-increment: page 2;

  1608 }

  1609 </pre>

  1610 </div>

  1612 <p>Additionally, a counter named ''pages'' is automatically created by the UA.

  1613 Its value is always the total number of pages in the document. (In continuous

  1614 media this is always 1.) The value of ''pages'' cannot be manipulated: while

  1615 'counter-reset' and 'counter-increment' statements that set it are valid, they

  1616 have no effect.

  1618 <p>In all other respects, page-associated counters behave as described in

  1619 [[!CSS21]], <a href="TR/CSS21/generate.html#scope">Nested Counters and

  1620 Scope</a> and <a href="http://www.w3.org/TR/CSS21/syndata.html#counter">Counters</a>.</p>

  1622 <h3 id="margin-text-alignment">Page-margin boxes and default values</h3>

  1624 <p>Properties used within page or margin contexts take their initial values from

  1625 their respective property definitions; however, user agents must behave as

  1626 though the values in the following table were established by rules in the UA

  1627 default style sheet.</p>

  1628 <table id="margin-values" class="data" summary="definition of page-margin box default properties">

  1629   <caption>Table 2. Default values for Page-Margin Boxes</caption>

  1630   <thead>

  1631     <tr>

  1632       <th>Page-margin box</th>

  1633       <th><span class="property">'text-align'</span></th>

  1634       <th><span class="property">'vertical-align'</span></th>

  1635     </tr>

  1636   </thead>

  1637   <tbody>

  1638     <tr>

  1639       <td><a href="#top-left-corner-box-def">top-left-corner</a></td>

  1640       <td>right</td>

  1641       <td>middle</td>

  1642       </tr>

  1643     <tr>

  1644       <td><a href="#top-left-box-def">top-left</a></td>

  1645       <td>left</td>

  1646       <td>middle</td>

  1647       </tr>

  1648     <tr>

  1649       <td><a href="#top-center-box-def">top-center</a></td>

  1650       <td>center</td>

  1651       <td>middle</td>

  1652       </tr>

  1653     <tr>

  1654       <td><a href="#top-right-box-def">top-right</a></td>

  1655       <td>right</td>

  1656       <td>middle</td>

  1657       </tr>

  1658     <tr>

  1659       <td><a href="#top-right-corner-box-def">top-right-corner</a></td>

  1660       <td>left</td>

  1661       <td>middle</td>

  1662       </tr>

  1663     <tr>

  1664       <td><a href="#left-top-box-def">left-top</a></td>

  1665       <td>center</td>

  1666       <td>top</td>

  1667       </tr>

  1668     <tr>

  1669       <td><a href="#left-middle-box-def">left-middle</a></td>

  1670       <td>center</td>

  1671       <td>middle</td>

  1672       </tr>

  1673     <tr>

  1674       <td><a href="#left-bottom-box-def">left-bottom</a></td>

  1675       <td>center</td>

  1676       <td>bottom</td>

  1677       </tr>

  1678     <tr>

  1679       <td><a href="#right-top-box-def">right-top</a></td>

  1680       <td>center</td>

  1681       <td>top</td>

  1682       </tr>

  1683     <tr>

  1684       <td><a href="#right-middle-box-def">right-middle</a></td>

  1685       <td>center</td>

  1686       <td>middle</td>

  1687       </tr>

  1688     <tr>

  1689       <td><a href="#right-bottom-box-def">right-bottom</a></td>

  1690       <td>center</td>

  1691       <td>bottom</td>

  1692       </tr>

  1693     <tr>

  1694       <td><a href="#bottom-left-corner-box-def">bottom-left-corner</a></td>

  1695       <td>right</td>

  1696       <td>middle</td>

  1697       </tr>

  1698     <tr>

  1699       <td><a href="#bottom-left-box-def">bottom-left</a></td>

  1700       <td>left</td>

  1701       <td>middle</td>

  1702       </tr>

  1703     <tr>

  1704       <td><a href="#bottom-center-box-def">bottom-center</a></td>

  1705       <td>center</td>

  1706       <td>middle</td>

  1707       </tr>

  1708     <tr>

  1709       <td><a href="#bottom-right-box-def">bottom-right</a></td>

  1710       <td>right</td>

  1711       <td>middle</td>

  1712       </tr>

  1713     <tr>

  1714       <td><a href="#bottom-right-corner-box-def">bottom-right-corner</a></td>

  1715       <td>left</td>

  1716       <td>middle</td>

  1717     </tr>

  1718   </tbody>

  1719 </table>

  1721 <div class="example">

  1723 <p>This example style sheet could be used to create a centered header with the

  1724 current chapter name:</p>

  1725 <pre>body {counter-reset: chapter;}

  1726 div.chapter {counter-increment: chapter;}

  1727 @page {

  1728 margin: 10%;

  1729 @top-center { content: "Chapter" counter(chapter) }

  1730 }

  1731 </pre>

  1732 </div>

  1734 <h2 id="page-size">Page Size</h2>

  1736 <p>People around the world use many different paper sizes. It is a goal of this

  1737 specification that web content should be adaptable to a range of different

  1738 sizes without having to write a specific style sheet for each paper size.</p>

  1740 <p>However, in some situations it is important that a certain page size achieves a

  1741 certain style. One way to achieve this goal is to utilize the 'size' property,

  1742 which indicates that the document should preferentially be displayed on a

  1743 surface of a certain size; another method is to use Media Queries [[MEDIAQ]]

  1744 which allow different style sheets to be applied to different page sizes.</p>

  1746 <h3 id="page-size-prop">Page size: the 'size' property</h3>

  1748 <table class="propdef" summary="definition of the size property">

  1749   <tr>

  1750     <th>Name:

  1751     <td><dfn id="size">size</dfn>

  1752   <tr>

  1753     <th>Value:

  1754     <td>&lt;length&gt;{1,2} | auto | [ &lt;page-size&gt; || [ portrait | landscape] ]

  1755   <tr>

  1756     <th>Initial:

  1757     <td>auto

  1758   <tr>

  1759     <td><em>Applies to:</em>

  1760     <td>page context

  1761   <tr>

  1762     <th>Inherited:

  1763     <td>N/A

  1764   <tr>

  1765     <th>Percentages:

  1766     <td>N/A

  1767   <tr>

  1768     <th>Media:

  1769     <td>paged

  1770   <tr>

  1771     <td><em>Computed value:</em>

  1772     <td>specified value

  1773 </table>

  1775 <p>This property specifies the target size and orientation of the

  1776 <a href="#page-box">page box</a>’s containing block.

  1777 In the general case, where one page box is rendered onto one <a href="#page-sheet">page sheet</a>,

  1778 the 'size' property also indicates the size of the destination page sheet.

  1780 <p>The size of a page box can either be "absolute" (fixed size) or "scalable"

  1781 (i.e., fitting available sheet sizes).

  1782 The first three values in the table below can be used to create scalable page

  1783 boxes.

  1784 Other values define a fixed-size page box, and thereby indicate the preferred

  1785 output media size. When possible, output should be rendered on the media size

  1786 indicated.

  1787 If the specified size is not available, the rules for

  1788 <a href="#renderingpages">transposing a page box to a different size</a>

  1789 apply.</p>

  1791 <p>If a <code>size</code> property declaration is qualified by a ''width'',

  1792 ''height'', ''device-width'', ''device-height'', ''aspect-ratio'',

  1793 ''device-aspect-ratio'' or ''orientation''

  1794 media query [[!MEDIAQ]] (or other conditional on the size of the paper), then

  1795 the declaration must be

  1796 <a href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignored</a>. Media

  1797 queries do not honor 'size': they assume the paper size that would be chosen

  1798 if no @page rules were specified.</p>

  1800 <p class=issue>It would be useful if media queries could respond at least

  1801 to sizes specified on an unqualified @page.

  1803 <div class="example">

  1804   <p>In the following example

  1805   <pre>

  1806   @page {

  1807     size: 4in 6in;

  1808   }

  1810   @media (max-width: 6in) {

  1811     @page {

  1812       size: letter;

  1813     }

  1814   }

  1815   </pre>

  1816   <p>The second <code>size</code> declaration is ignored, i.e. the specified value

  1817   of the <code>size</code> property is <code>4in 6in</code>.

  1818 </div>

  1820 <table class="page-sizes">

  1821 <tr>

  1822 <th>Value</th>

  1823 <th>Description</th>

  1824 </tr>

  1825 <tr>

  1826 <td>auto</td>

  1827 <td>The page box will be set to a size and orientation chosen by the UA. In the

  1828 usual case, the page box size and orientation is chosen to match the target

  1829 media sheet.</td>

  1830 </tr>

  1831 <tr>

  1832 <td>landscape</td>

  1833 <td>Specifies that the page's content be printed in landscape orientation. The

  1834 longer sides of the page box are horizontal. If a <span class="css">'&lt;page-size&gt;'</span> is not specified, the size of the page sheet

  1835 is chosen by the UA.</td>

  1836 </tr>

  1837 <tr>

  1838 <td>portrait</td>

  1839 <td>Specifies that the page's content be printed in portrait orientation. The

  1840 shorter sides of the page box are horizontal. If a <span class="css">'&lt;page-size&gt;'</span> is not specified, the size of the page sheet

  1841 is chosen by the UA.</td>

  1842 </tr>

  1843 <tr>

  1844 <td>&lt;length&gt;</td>

  1845 <td>The page box will be set to the given absolute dimension(s). If only one length

  1846 value is specified, it sets both the width and height of the page box (i.e.,

  1847 the box is a square). If two length values are specified, the first establishes

  1848 the page box width, and the second the page box height. Values in units of

  1849 <span class="css">'em'</span> and <span class="css">'ex'</span> refer to the

  1850 page context's font. Negative lengths are illegal.</td>

  1851 </tr>

  1852 <tr>

  1853 <td>&lt;page-size&gt;</td>

  1854 <td>A page size can be specified using one of the following media names. This is

  1855 the equivalent of specifying the <span class="css">'&lt;page-size&gt;'</span>

  1856 using length values. The definition of the the media names comes from

  1857 <cite>Media Standardized Names</cite> [[!PWGMSN]].

  1859 <dl>

  1861 <dt>A5</dt>

  1862 <dd>Equivalent to the size of ISO A5 media: 148mm wide and 210 mm high.</dd>

  1864 <dt>A4</dt>

  1865 <dd>Equivalent to the size of ISO A4 media: 210 mm wide and 297 mm high.</dd>

  1867 <dt>A3</dt>

  1868 <dd>Equivalent to the size of ISO A3 media: 297mm wide and 420mm high.</dd>

  1870 <dt>B5</dt>

  1871 <dd>Equivalent to the size of ISO B5 media: 176mm wide by 250mm high.</dd>

  1873 <dt>B4</dt>

  1874 <dd>Equivalent to the size of ISO B4 media: 250mm wide by 353mm high.</dd>

  1876 <dt>letter</dt>

  1877 <dd>Equivalent to the size of North American letter media: 8.5 inches wide and 11

  1878 inches high</dd>

  1880 <dt>legal</dt>

  1881 <dd>Equivalent to the size of North American legal: 8.5 inches wide by 14 inches

  1882 high.</dd>

  1884 <dt>ledger</dt>

  1885 <dd>Equivalent to the size of North American ledger: 11 inches wide by 17 inches

  1886 high.</dd>

  1887 </dl></td>

  1888 </tr>

  1889 </table>

  1891 <p>The '&lt;page-size&gt;' names can be used in conjunction with 'landscape' or

  1892 'portrait' to indicate both size and orientation.</p>

  1894 <h4>Some examples:</h4>

  1896 <div class="example">

  1897 <pre>

  1898 @page {

  1899 size: A4 landscape;

  1900 }

  1901 </pre>

  1903 <p>The above example sets the width of the page box to be 297mm and the height to

  1904 be 210mm. The page box in this example should be rendered on a page sheet size

  1905 of 210 mm by 297 mm.</p>

  1906 </div>

  1908 <div class="example">

  1910 <p>In the following example, the outer edges of the page box will align with the

  1911 page. The percentage value on the <span class="property">'margin'</span>

  1912 property is relative to the page size so if the page sheet dimensions are 210mm

  1913 x 297mm (i.e., A4), the margins are 21mm and 29.7mm. Assuming there are no page

  1914 borders or padding set in the UA default style sheet, the resulting page area

  1915 is 189mm by 367.3mm (210mm-21mm by 297mm-29.7mm).</p>

  1916 <pre>

  1917 @page {

  1918 size: auto;/* auto is the initial value */

  1919 margin: 10%;

  1920 }

  1921 </pre>

  1922 </div>

  1924 <div class="example">

  1925 <pre>

  1926 @page {

  1927 size: 8.5in 11in;/* width height */

  1928 }

  1929 </pre>

  1931 <p>The above example sets the width of the page box to be 8.5 inches and the

  1932 height to be 11 inches. This indicates that the page sheet size should be

  1933 8.5"x11" and the orientation 'portrait'.</p>

  1934 </div>

  1936 <h4 id="page-size-media-query">Media Queries</h4>

  1938 <p>This section is informative.</p>

  1940 <p>By using Media Queries [[MEDIAQ]], one style sheet can express different

  1941 stylistic preferences for different page sizes. Consider this example:</p>

  1943 <div class="example" style="font-size: 10pt;">

  1944 <pre>

  1945  /* style sheet for "A4" printing */

  1946  @media print and (width: 21cm) and (height: 29.7cm) {

  1947     @page {

  1948        margin: 3cm;

  1949     }

  1950  }

  1952  /* style sheet for "letter" printing */

  1953  @media print and (width: 8.5in) and (height: 11in) {

  1954     @page {

  1955         margin: 1in;

  1956     }

  1957  }

  1958 </pre>

  1959 </div>

  1961 <p>In the example above, "A4" sheets are given a "3cm" page margin, and "letter"

  1962 sheets are given a "1in" page margin.</p>

  1964 <h3 id="renderingpages">Rendering page boxes that do not fit a page sheet</h3>

  1966 <p>If a page box does not match the target page sheet dimensions, the user agent

  1967 should do one of the following (in order of preference):</p>

  1969 <ol>

  1970   <li>Render the page box at the indicated size on a larger page sheet.</li>

  1971   <li>Rotate the page box 90° if this will make the page box fit the page sheet.</li>

  1972   <li>Scale the page box to fit the page sheet. (The aspect ratio of the page box

  1973   <em class="RFC2119">should</em> be preserved.)</li>

  1974   <li>Reformat the page contents, including 'spilling' onto other page sheets.</li>

  1975   <li>Clip overflowed content (least preferred).</li>

  1976 </ol>

  1978 <p>The user agent <em class="RFC2119">MAY</em> wish to consult the user before

  1979 performing these operations.</p>

  1981 <h3 id="positioning-page-box">Positioning the page box on the sheet</h3>

  1983 <p>When the page box is smaller than the page size, the user agent <em class="RFC2119">SHOULD</em> either:</p>

  1985 <ul>

  1986   <li>center the page box on the sheet since this will align double-sided pages

  1987   and avoid accidental loss of information that is printed near the edge of the

  1988   sheet; or</li>

  1989   <li>position the page box in the upper left corner of the page sheet, as this

  1990   may minimize media consumption.</li>

  1991 </ul>

  1993 <p>The user agent <em class="RFC2119">MAY</em> wish to consult the user in this

  1994 regard.</p><!-- "Page selector and page context" -->

  1996 <h2 id="page-breaks">

  1997     <a id="pg-br-before-after"></a>

  1998     <a id="page-break-before"></a>

  1999     <a id="page-break-after"></a>

  2000     <a id="page-break-inside"></a>

  2001     <a id="breaks-inside"></a>

  2002     <a id="orphans"></a>

  2003     <a id="widows"></a>

  2004     <a id="allowed-pg-brk"></a>

  2005     <a id="brk-btw-blocks"></a>

  2006     <a id="brk-btw-lines"></a>

  2007     <a id="brk-end-block"></a>

  2008     <a id="forced-pg-brk"></a>

  2009     <a id="best-pg-brk"></a>

  2010     Page Breaks

  2011 </h2>

  2013 <p>

  2014   The CSS Fragmentation Module [[!CSS3-BREAK]] module

  2015   defines how and where CSS boxes

  2016   can be <i>fragmented</i>, including across page breaks.

  2017   It defines a few properties that indicate where the user agent

  2018   <em class="RFC2119">MAY</em> or <em class="RFC2119">MUST</em> break pages,

  2019   and on what page (left or right) the subsequent content resumes.

  2020   Each page break ends layout in the current <a href="#page-box">page box</a>

  2021   and causes remaining pieces of the document tree to be laid out

  2022   in a new page box.

  2023 </p>

  2025 <h3 id="using-named-pages">Using named pages: 'page'</h3>

  2026 <table class="propdef" summary="property definition">

  2027   <tr>

  2028     <th>Name:

  2029     <td><dfn id="page">page</dfn>

  2030   <tr>

  2031     <th>Value:

  2032     <td>auto | &lt;identifier&gt;

  2033   <tr>

  2034     <th>Initial:

  2035     <td>auto

  2036   <tr>

  2037     <th>Applies to:

  2038     <td>boxes that create <a href="http://www.w3.org/TR/css3-break/#btw-blocks">class 1</a> break points

  2039   <tr>

  2040     <th>Inherited:

  2041     <td>no (but see prose)

  2042   <tr>

  2043     <th>Percentages:

  2044     <td>N/A

  2045   <tr>

  2046     <th>Media:

  2047     <td>paged

  2048   <tr>

  2049     <th>Computed value:

  2050     <td>specified value

  2051 </table>

  2053 <p>

  2054   The 'page' property is used to specify a particular type of page (called a <dfn>named page</dfn>)

  2055   on which an element <em class="RFC2119">MUST</em> be displayed.

  2056   If necessary, a <i>forced page break</i> is introduced

  2057   and a new page generated of the specified type.

  2059 <p>

  2060   Page names are case-sensitive identifiers.

  2061   However the ''auto'' value, being a CSS keyword, is

  2062   <a href="http://www.w3.org/TR/CSS21/syndata.html#characters">ASCII case-insensitive</a>.

  2064 <div class="example">

  2066 <p>This example will put all tables on a right-hand side landscape page (named

  2067 "rotated"):</p>

  2068 <pre>

  2069 @page rotated { size: landscape }

  2070 table { page: rotated; break-before: right }

  2071 </pre>

  2072 </div>

  2074 <p>

  2075   The 'page' property works as follows:

  2077 <ol>

  2079   <li>

  2080     First, any ''auto'' values are resolved against non-''auto'' ancestors

  2081     (as specified below).

  2083   <li>

  2084     Next,

  2085     a <dfn>preceding 'page' value</dfn> and <dfn>succeeding 'page' value</dfn>

  2086     is determined for each box

  2087     as the value (if any) propagated from its last or first child (respectively),

  2088     else the used value on the box itself.

  2089     A child propagates its own <i title="preceding page value">preceding</i> or <i>succeeding 'page' value</i>

  2090     if and only if the 'page' property applies to it.

  2092   <li>

  2093     If for any two boxes meeting at a <a href="http://www.w3.org/TR/css3-break/#btw-blocks">Class 1</a> break point,

  2094     the <i>preceding 'page' value</i> and <i>succeeding 'page' value</i> do not match,

  2095     then a page break is forced between the two boxes,

  2096     and content after the break resumes on a page box of the named type.

  2097 </ol>

  2099 <p>

  2100   Essentially, the two 'page' values compared are those from the deepest boxes

  2101   meeting at the class 1 break point,

  2102   ignoring any subtrees rooted by boxes to which the 'page' property does not apply.

  2104 <p>

  2105   The 'page' property does not inherit.

  2106   However, if the 'page' value on an element is ''auto'',

  2107   then its used value is the value specified on its nearest ancestor with a non-auto value.

  2108   When specified on the root element, the effective name is the empty string.

  2110   <!-- See http://www.w3.org/TR/2007/WD-css3-gcpm-20070504/#named3 -->

  2112 <p>

  2113   Because a previous version of this specification indicated that the 'page' property is inherited,

  2114   an implementation that inherits the 'page' property

  2115   and treats ''auto'' as always naming the empty string

  2116   remains conformant to CSS3 Paged Media.

  2117   Therefore authors should not explicitly specify the ''auto'' value

  2118   on a descendant of an element with a non-''auto'' value,

  2119   as the resulting behavior will be unpredictable.

  2121 <p>See [[!CSS3-BREAK]] for additional details on page breaks.

  2123 <div class="example">

  2125 <p>In this example, the two tables are rendered on landscape pages (indeed, on the

  2126 same page, if they fit). The page type "narrow" is used for the &lt;p&gt; after

  2127 the second table, as the page properties for the table element are no longer in

  2128 effect:</p>

  2129 <pre>

  2130 @page narrow { size: 9cm 18cm }

  2131 @page rotated { size: landscape }

  2132 div { page: narrow }

  2133 table { page: rotated }

  2134 </pre>with this document:

  2135 <pre>

  2136 &lt;div&gt;

  2137 &lt;table&gt;...&lt;/table&gt;

  2138 &lt;table&gt;...&lt;/table&gt;

  2139 &lt;p&gt;This text is rendered on a 'narrow' page&lt;/p&gt;

  2140 &lt;/div&gt;

  2141 </pre>

  2142 </div>

  2144 <div class="example">

  2145   <p>In Japanese documents, sometimes different parts of a single document

  2146   will have different <i lang="ja-Latn">kihon hanmen</i>. [[JLREQ]]

  2147   The 'page' property, together with ''@page'' rules specifying different page widths,

  2148   can accomodate this type of layout:

  2149   <pre>

  2150 &lt;!DOCTYPE html>

  2151 &lt;html lang="ja">

  2152   &lt;style>

  2153     html   { writing-mode: vertical-rl;

  2154              line-height: 1.6; }

  2155     .main  { page: main;

  2156              columns: 2; column-gap: 1rem; }

  2157     .index { page: index;

  2158              columns: 3; column-gap: 1rem; }

  2159     @page       { margin: auto;    /* center kihon hanmen on page */

  2160                   width:  40rem; } /* 1.6 &times; 25 lines        */

  2161     @page main  { height: 61rem; } /* 2 &times; 30 chars + 1 &times; gap */

  2162     @page index { height: 62rem; } /* 3 &times; 20 chars + 2 &times; gap */

  2163   &lt;/style>

  2164   &lt;section class="main"> ... &lt;/section>

  2165   &lt;section class="index"> ... &lt;/section>

  2166 &lt;/html>

  2167 </pre>

  2168 </div>

  2171 <h2 id="image-properties">Image Properties</h2>

  2173 <p class="note">This section has been moved to [[CSS3-IMAGES]].</p>

  2175 <h2 class="no-num" id="properties-list">Appendix A: Applicable CSS2.1 Properties</h2>

  2177 <h3 class="no-num">Properties that apply within the page context</h3>

  2179 <p>The following CSS 2.1 [[!CSS21]] properties apply to the page box.

  2180 If a conforming user agent supports any of these properties on block

  2181 boxes, then it must also support that property for the page box.</p>

  2183 <table class="property-list">

  2184   <tbody>

  2185     <tr><td rowspan="2"><a href="http://www.w3.org/TR/CSS21/visuren.html#direction">bidi properties</a>

  2186         <td>direction

  2187   <tbody>

  2188     <tr><td rowspan="6"><a href="http://www.w3.org/TR/CSS21/colors.html#background-properties">background properties</a>

  2189         <td>background-color

  2190     <tr><td>background-image

  2191     <tr><td>background-repeat

  2192     <tr><td>background-attachment

  2193     <tr><td>background-position

  2194     <tr><td>background

  2195   <tbody>

  2196     <tr><td rowspan="20"><a href="http://www.w3.org/TR/CSS21/box.html#border-properties">border properties</a>

  2197         <td>border-top-width

  2198     <tr><td>border-right-width

  2199     <tr><td>border-bottom-width

  2200     <tr><td>border-left-width

  2201     <tr><td>border-width

  2202     <tr><td>border-top-color

  2203     <tr><td>border-right-color

  2204     <tr><td>border-bottom-color

  2205     <tr><td>border-left-color

  2206     <tr><td>border-color

  2207     <tr><td>border-top-style

  2208     <tr><td>border-right-style

  2209     <tr><td>border-bottom-style

  2210     <tr><td>border-left-style

  2211     <tr><td>border-short-style

  2212     <tr><td>border-top

  2213     <tr><td>border-right

  2214     <tr><td>border-bottom

  2215     <tr><td>border-left

  2216     <tr><td>border

  2217   <tbody>

  2218     <tr><td rowspan="2"><a href="http://www.w3.org/TR/CSS21/generate.html#counters">counter properties</a>

  2219         <td>counter-reset

  2220     <tr><td>counter-increment

  2221   <tbody>

  2222     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/colors.html#propdef-color">color</a>

  2223   <tbody>

  2224     <tr><td rowspan="6"><a href="http://www.w3.org/TR/CSS21/fonts.html">font properties</a>

  2225         <td>font-family

  2226     <tr><td>font-size

  2227     <tr><td>font-style

  2228     <tr><td>font-variant

  2229     <tr><td>font-weight

  2230     <tr><td>font

  2231   <tbody>

  2232     <tr><td rowspan="3"><a href="http://www.w3.org/TR/CSS21/visudet.html#the-height-property">height</a> <a href="http://www.w3.org/TR/CSS21/visudet.html#min-max-heights">properties</a>

  2233         <td>height

  2234     <tr><td>min-height

  2235     <tr><td>max-height

  2236   <tbody>

  2237     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/visudet.html#line-height">line-height</a>

  2238   <tbody>

  2239     <tr><td rowspan="5"><a href="http://www.w3.org/TR/CSS21/box.html#margin-properties">margin properties</a>

  2240         <td>margin-top

  2241     <tr><td>margin-right

  2242     <tr><td>margin-bottom

  2243     <tr><td>margin-left

  2244     <tr><td>margin

  2245   <tbody>

  2246     <tr><td rowspan="5"><a href="http://www.w3.org/TR/CSS21/ui.html#dynamic-outlines">outline properties</a>

  2247         <td>outline-width

  2248     <tr><td>outline-style

  2249     <tr><td>outline-color

  2250     <tr><td>outline

  2251   <tbody>

  2252     <tr><td rowspan="5"><a href="http://www.w3.org/TR/CSS21/box.html#padding-properties">padding properties</a>

  2253         <td>padding-top

  2254     <tr><td>padding-right

  2255     <tr><td>padding-bottom

  2256     <tr><td>padding-left

  2257     <tr><td>padding

  2258   <tbody>

  2259     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/generate.html#quotes-specify">quotes</a>

  2260   <tbody>

  2261     <tr><td rowspan="8"><a href="http://www.w3.org/TR/CSS21/text.html">text properties</a>

  2262         <td>direction

  2263     <tr><td>letter-spacing

  2264     <tr><td>text-align

  2265     <tr><td>text-decoration

  2266     <tr><td>text-indent

  2267     <tr><td>text-transform

  2268     <tr><td>white-space

  2269     <tr><td>word-spacing

  2270   <tbody>

  2271     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/visufx.html#visibility">visibility</a>

  2272   <tbody>

  2273     <tr><td rowspan="3"><a href="http://www.w3.org/TR/CSS21/visudet.html#the-width-property">width</a> <a href="http://www.w3.org/TR/CSS21/visudet.html#min-max-widths">properties</a>

  2274         <td>width

  2275     <tr><td>min-width

  2276     <tr><td>max-width

  2277 </table>

  2279 <p>Properties that apply to the page-margin boxes can also be set within

  2280 the page context: if inheritable or explicitly inherited (with the

  2281 <code>inherit</code> keyword in the margin context), they will inherit

  2282 to the page-margin boxes.</p>

  2284 <h3 class="no-num">Properties that apply within the margin contexts</h3>

  2286 <p>The following CSS 2.1 [[!CSS21]] properties apply to page-margin boxes.

  2287 If a conforming user agents supports any of these properties on block

  2288 boxes, then it must also support that property for page-margin boxes (except

  2289 for <code>z-index</code>, which is optional for page-margin boxes).</p>

  2291 <table class="property-list">

  2292   <tbody>

  2293     <tr><td rowspan="2"><a href="http://www.w3.org/TR/CSS21/visuren.html#direction">bidi properties</a>

  2294         <td>direction

  2295     <tr><td>unicode-bidi

  2296   <tbody>

  2297     <tr><td rowspan="6"><a href="http://www.w3.org/TR/CSS21/colors.html#background-properties">background properties</a>

  2298         <td>background-color

  2299     <tr><td>background-image

  2300     <tr><td>background-repeat

  2301     <tr><td>background-attachment

  2302     <tr><td>background-position

  2303     <tr><td>background

  2304   <tbody>

  2305     <tr><td rowspan="20"><a href="http://www.w3.org/TR/CSS21/box.html#border-properties">border properties</a>

  2306         <td>border-top-width

  2307     <tr><td>border-right-width

  2308     <tr><td>border-bottom-width

  2309     <tr><td>border-left-width

  2310     <tr><td>border-width

  2311     <tr><td>border-top-color

  2312     <tr><td>border-right-color

  2313     <tr><td>border-bottom-color

  2314     <tr><td>border-left-color

  2315     <tr><td>border-color

  2316     <tr><td>border-top-style

  2317     <tr><td>border-right-style

  2318     <tr><td>border-bottom-style

  2319     <tr><td>border-left-style

  2320     <tr><td>border-short-style

  2321     <tr><td>border-top

  2322     <tr><td>border-right

  2323     <tr><td>border-bottom

  2324     <tr><td>border-left

  2325     <tr><td>border

  2326   <tbody>

  2327     <tr><td rowspan="2"><a href="http://www.w3.org/TR/CSS21/generate.html#counters">counter properties</a>

  2328         <td>counter-reset

  2329     <tr><td>counter-increment

  2330   <tbody>

  2331     <tr><td colspan="2"><a href="">content</a>

  2332   <tbody>

  2333     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/colors.html#propdef-color">color</a>

  2334   <tbody>

  2335     <tr><td rowspan="6"><a href="http://www.w3.org/TR/CSS21/fonts.html">font properties</a>

  2336         <td>font-family

  2337     <tr><td>font-size

  2338     <tr><td>font-style

  2339     <tr><td>font-variant

  2340     <tr><td>font-weight

  2341     <tr><td>font

  2342   <tbody>

  2343     <tr><td rowspan="3"><a href="http://www.w3.org/TR/CSS21/visudet.html#the-height-property">height</a> <a href="http://www.w3.org/TR/CSS21/visudet.html#min-max-heights">properties</a>

  2344         <td>height

  2345     <tr><td>min-height

  2346     <tr><td>max-height

  2347   <tbody>

  2348     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/visudet.html#line-height">line-height</a>

  2349   <tbody>

  2350     <tr><td rowspan="5"><a href="http://www.w3.org/TR/CSS21/box.html#margin-properties">margin properties</a>

  2351         <td>margin-top

  2352     <tr><td>margin-right

  2353     <tr><td>margin-bottom

  2354     <tr><td>margin-left

  2355     <tr><td>margin

  2356   <tbody>

  2357     <tr><td rowspan="5"><a href="http://www.w3.org/TR/CSS21/ui.html#dynamic-outlines">outline properties</a>

  2358         <td>outline-width

  2359     <tr><td>outline-style

  2360     <tr><td>outline-color

  2361     <tr><td>outline

  2362   <tbody>

  2363     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/visufx.html#overflow">overflow</a>

  2364   <tbody>

  2365     <tr><td rowspan="5"><a href="http://www.w3.org/TR/CSS21/box.html#padding-properties">padding properties</a>

  2366         <td>padding-top

  2367     <tr><td>padding-right

  2368     <tr><td>padding-bottom

  2369     <tr><td>padding-left

  2370     <tr><td>padding

  2371   <tbody>

  2372     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/generate.html#quotes-specify">quotes</a>

  2373   <tbody>

  2374     <tr><td rowspan="7"><a href="http://www.w3.org/TR/CSS21/text.html">text properties</a>

  2375         <td>letter-spacing

  2376     <tr><td>text-align

  2377     <tr><td>text-decoration

  2378     <tr><td>text-indent

  2379     <tr><td>text-transform

  2380     <tr><td>white-space

  2381     <tr><td>word-spacing

  2382   <tbody>

  2383     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/visudet.html#line-height">vertical-align</a>

  2384   <tbody>

  2385     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/visufx.html#visibility">visibility</a>

  2386   <tbody>

  2387     <tr><td rowspan="3"><a href="http://www.w3.org/TR/CSS21/visudet.html#the-width-property">width</a> <a href="http://www.w3.org/TR/CSS21/visudet.html#min-max-widths">properties</a>

  2388         <td>width

  2389     <tr><td>min-width

  2390     <tr><td>max-width

  2391   <tbody>

  2392     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/visuren.html#z-index">z-index</a>

  2393 </table>

  2395 <h2 class="no-num" id="transfer-possibilities">Appendix B: Transfer Possibilities</h2>

  2397 <p>Often, but not always, the page box has a one-to-one correspondence to the

  2398 physical surface onto which the document is ultimately rendered. The CSS3 page

  2399 model specifies formatting within the page box, but it is the user agent's

  2400 responsibility to transfer the page box to the sheet. Some user agent transfer

  2401 possibilities that are not addressed by CSS3 include:</p>

  2403 <ul id="complex-usecases">

  2404   <li>Transferring one page box to one sheet (e.g. single-sided printing);</li>

  2405   <li>Transferring two page boxes to the front and back surfaces of the same

  2406   sheet (e.g. double-sided printing);</li>

  2407   <li>Transferring N (small) page boxes to one sheet (called "N-up");</li>

  2408   <li>Transferring one (large) page box to N x M sheets (called "tiling");</li>

  2409   <li>Creating signatures. A <dfn>signature</dfn> is a group of pages printed on

  2410   a sheet, which, when folded and trimmed like a book, appear in their proper

  2411   sequence;</li>

  2412   <li>Printing one document to multiple output trays;</li>

  2413   <li>Generating files containing print instructions.</li>

  2414 </ul>

  2416 <h2 class="no-num" id="changes">Changes</h2>

  2418 <p>

  2419   Changes since the <a href="http://www.w3.org/TR/2006/WD-css3-page-20061010/">10 October 2006 Working Draft</a> are:

  2420 </p>

  2422 <ul>

  2423   <li>The '':blank'' <a href="#pseudo-classes">pseudo-class</a> was imported

  2424     from the <a href="http://dev.w3.org/csswg/css3-gcpm/">Generated Content for Paged Media</a> module.

  2426   <li>''@page'' rules can now take multiple comma separated selectors,

  2427     each selector can have multiple pseudo-classes.

  2429     <div class="example">

  2430       <pre>@page :first, :blank { @bottom-center { content: none } }</pre>

  2431       <pre>@page :first:left { @bottom-left { content: none } }</pre>

  2432     </div>

  2434   <li>Margin boxes are renamed <a href="#margin-boxes">page-margin boxes</a>,

  2435     to avoid confusion with the margin area of each box.

  2437   <li>The <a href="#variable-sizing">Variable Dimension</a>

  2438     layout rules for page-margin boxes have been much simplified

  2439     to not require quadratic optimization.

  2441   <li>The relative <a href="#painting">painting order</a>

  2442     of page-margin boxes and page content has changed.

  2444   <li>The description of page breaks and definition of related properties

  2445     (except for the 'page' property)

  2446     have been moved to the CSS Fragmentation Module. [[!CSS3-BREAK]]

  2448   <li>The 'fit' and 'fit-position' properties

  2449     are renamed to 'object-fit' and 'object-position',

  2450     redefined to enable additional use cases,

  2451     and moved to the CSS3 Image Values and Replaced Content module.

  2452     [[CSS3-IMAGES]]

  2454   <li>Many miscellaneous clarifications

  2455     and editorial improvements have been incorporated.

  2457 </ul>

  2460 <h2 class="no-num" id="references">References</h2>

  2462 <h3 class="no-num" id="normative-references">Normative References</h3><!--normative-->

  2464 <h3 class="no-num" id="informative-references">Informative References</h3><!--informative-->

  2465 </div>

  2466 </div>

  2467 </body>

  2468 </html>

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