drafts: css-page/Overview.src.html@07124102230d

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     5 CSS Paged Media Module Level 3

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    82 <div>

    83 <div class="head">

    84 <!--logo-->

    85 <h1 class="p-name">CSS Paged Media Module Level 3</h1>

    86 <h2 class="no-num no-toc" id="w3c-working">[LONGSTATUS] <span class="dt-updated"><span class="value-title" title="[CDATE]">[DATE]</span></span></h2>

    87 <dl>

    88   <dt>This version:</dt>

    89   <dd><a class="u-url" href="http://dev.w3.org/csswg/css3-page/">http://dev.w3.org/csswg/css3-page/</a></dd>

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

    92   <dt>Latest version:</dt>

    93   <dd><a href="http://www.w3.org/TR/css3-page/">http://www.w3.org/TR/css3-page/</a></dd>

    95   <dt>Editor’s Draft:</dt>

    96   <dd><a href="http://dev.w3.org/csswg/css3-page/">http://dev.w3.org/csswg/css3-page/</a></dd>

    98   <dt>Previous version:</dt>

    99   <dd><a rel="previous" href="http://www.w3.org/TR/2013/WD-css3-page-20130314/">http://www.w3.org/TR/2013/WD-css3-page-20130314/</a></dd>

   101   <dt>Issue Tracking:</dt>

   102   <dd><a rel="issues" href="http://www.w3.org/Style/CSS/Tracker/products/13">http://www.w3.org/Style/CSS/Tracker/products/13</a>

   104   <dt>Feedback:</dt>

   105     <dd><a href="mailto:www-style@w3.org?subject=%5Bcss-page%5D%20feedback"

   106          >www-style@w3.org</a>

   107          with subject line &ldquo;<kbd>[css-page]

   108          <var>&hellip; message topic &hellip;</var></kbd>&rdquo;

   109          (<a rel="discussion" href="http://lists.w3.org/Archives/Public/www-style/"

   110            >archives</a>)

   112   <dt>Editors:</dt>

   113     <dd class="p-author h-card vcard">

   114      <span class="p-name fn">Melinda Grant</span>,

   115      <span class="p-org org">Hewlett-Packard</span></dd>

   116     <dd class="p-author h-card vcard">

   117      <span class="p-name fn">H&aring;kon Wium Lie</span>,

   118      <span class="p-org org">Opera Software</span></dd>

   119     <dd class="p-author h-card vcard">

   120      <span class="p-name fn">Elika J. Etemad</span>,

   121      <span class="p-org org">Mozilla</span></dd>

   122     <dd class="p-author h-card vcard">

   123      <span class="p-name fn">Simon Sapin</span>,

   124      <span class="p-org org">Kozea</span></dd>

   125 </dl>

   127 <!--copyright-->

   129 </div>

   130 <hr title="Separator for header">

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

   134 <p>

   135   <span class="p-summary">

   136 This module describes the page model that partitions a flow into pages. It

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

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

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

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

   141 to enable page numbering and running headers / footers.  </span>

   142 </p>

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

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

   148 <!--status-->

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

   151 <!--end-toc-->

   152 <!-- "Introduction" -->

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

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

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

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

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

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

   161 <ul>

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

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

   164   padding are specified;</li>

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

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

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

   168 </ul>

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

   171 document is formatted within a rectangular area, called the

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

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

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

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

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

   178 size.</p>

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

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

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

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

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

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

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

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

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

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

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

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

   194 2119</cite> [[!RFC2119]]. However, for readability, these words do not appear

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

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

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

   199   like this:

   201 <div class="example">

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

   203 </div>

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

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

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

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

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

   213 page model:</p>

   215 <dl>

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

   217   <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"

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

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

   220   corner of a page sheet.</dd>

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

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

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

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

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

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

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

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

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

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

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

   233   device dependent within the constraints expressed in the sections

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

   257   reverse-landscape renderings.</span>

   258   </dd>

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

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

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

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

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

   265   not it actually is.</dd>

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

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

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

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

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

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

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

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

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

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

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

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

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

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

   282   orientation.</dd>

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

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

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

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

   288   the left page can be specified using the '':left'' <i>page selector</i>.

   289   </dd>

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

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

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

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

   295   to the right page can be specified using the '':right'' <i>page selector</i>.

   296   </dd>

   297 </dl>

   300 <h2 id="page-model">The Page Model</h2>

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

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

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

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

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

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

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

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

   312 <p class="issue">

   313     In CSS 2.1, both the page box and page area are simple rectangles.

   314     Neither is a CSS box with margins, borders, and padding.

   315     This CSS box should be distinct from the page box and page area,

   316     which would be its margin area and content area, respectively.

   317     Naming ideas?

   319 <ul>

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

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

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

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

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

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

   326   of the document.</li>

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

   328   16 <dfn>page-margin boxes</dfn>.

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

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

   331 </ul>

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

   351 margin edges of the page box.

   353 <h3 id="painting">

   354 Page Backgrounds and Painting Order</h3>

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

   357   following painting order (bottommost first):

   359   <ol>

   360     <li>page background

   361     <li>document canvas

   362     <li>page borders

   363     <li>document contents

   364     <li>page-margin boxes

   365   </ol>

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

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

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

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

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

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

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

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

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

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

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

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

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

   381   or page area as usual.

   383   <p>

   384   With respect to the page-margin boxes,

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

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

   387   that establishes a

   388   <a href="http://www.w3.org/TR/CSS21/visuren.html#x43">stacking context</a>

   389   [[!CSS21]]:

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

   391   or between the content and the canvas.

   392   They may only paint in front of the document content

   393   or behind the document canvas.

   394   The page background is always painted underneath everything else.

   396   <p>The 'z-index' property applies to page-margin boxes.

   397   Since the 'position' property does not apply to page-margin boxes,

   398   'z-index' always affects page-margin boxes as if they were positioned elements

   399   regardless of the 'position' property's value.

   400   Each page-margin boxes always establishes a stacking context.

   402   <p>The default painting order,

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

   404   of page-margin boxes with respect to each other is as follows:

   406   <ol>

   407     <li>''@top-left-corner''

   408     <li>''@top-left''

   409     <li>''@top-center''

   410     <li>''@top-right''

   411     <li>''@top-right-corner''

   413     <li>''@right-top''

   414     <li>''@right-middle''

   415     <li>''@right-bottom''

   417     <li>''@bottom-right-corner''

   418     <li>''@bottom-right''

   419     <li>''@bottom-center''

   420     <li>''@bottom-left''

   421     <li>''@bottom-left-corner''

   423     <li>''@left-bottom''

   424     <li>''@left-middle''

   425     <li>''@left-top''

   426   </ol>

   428   <p class=note>

   429     Start with ''@top-left-corner'', then go clockwise.

   430     This order is arbitrary but can be overridden with 'z-index'.

   431     It only has a visible effect when page-margin boxes overlap,

   432     which should not happen in most cases.

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

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

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

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

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

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

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

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

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

   445 observe the following general principles concerning content outside the page

   446 box:</p>

   448 <ul>

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

   450   to "bleed".

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

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

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

   454   intent).

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

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

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

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

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

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

   461   content-empty page.

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

   463   boxes is sometimes necessary to honor the forced-break values for

   464   'page-break-before'/'break-before' and 'page-break-after'/'break-after'.

   465   [[!CSS21]] [[!CSS3-BREAK]]</li>

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

   468   inconvenient locations just to avoid rendering them. Instead:

   469   <ul>

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

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

   472     property.</li>

   473     </ul></li>

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

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

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

   477 </ul>

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

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

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

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

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

   485 pseudo-classes</a>.

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

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

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

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

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

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

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

   494 page, and vice versa.</p>

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

   498 <ul>

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

   500   same as the inline progression.</li>

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

   502   same as the block progression.</li>

   503 </ul>

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

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

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

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

   509 properties on the root element.</p>

   511 <p>

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

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

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

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

   516   (and the <code>:first</code> pseudo-class matches the first printed page).

   518 <div class="example">

   519 <pre>

   520 html { break-before: always }

   521 </pre>

   523 <p>

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

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

   526   to print on a ':left' page

   527 </p>

   529 <pre>

   530 html { break-before: left }

   531 </pre>

   533 <p>

   534   For an HTML document,

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

   536   to print on a ':left' page,

   537   regardless of the page progression.

   538 </p>

   539 </div>

   541 <h2 id="page-selector-and-context">

   542 Page Selectors and the Page Context</h2>

   544 <h3 id="at-page-rule"><a id="page-box-page-rule"></a>

   545 The @page Rule</h3>

   547   <p>Authors can specify various aspects of a page box,

   548   such as its dimensions, orientation, and margins,

   549   within an ''@page'' rule.

   550   ''@page'' rules are allowed

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

   552   An ''@page'' rule consists of the keyword ''@page'',

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

   554   <a href="#page-selectors">page selectors</a>

   555   and a block of declarations

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

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

   558   interleaved between declarations.

   559   The current level of this specification

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

   562   <p>''@page'' rules without a selector list apply to every page.

   563   Other ''@page'' rules apply to pages that <i>match</i>

   564   at least one of their selectors.

   565   Properties declared within the page context apply to the page box.

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

   569 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>

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

   573 <h3 id="page-selectors">Page selectors</h3>

   575   <p>A <dfn id="page-selector">page selector</dfn> is made of

   576   either a <i>page type selector</i>

   577   or a <i>page pseudo-class</i>,

   578   followed by zero or more additional <i>page pseudo-classes</i>.

   579   No whitespace is allowed between components of a selector.

   580   The <i title="page_selector">page selector grammar</i>

   581   and examples can be found below.

   583   <p>A <i>page selector</i> is said to <dfn>match</dfn> a given page if and only if

   584   all of its components match the page.

   586   <p>A <dfn>page type selector</dfn> is

   587   a case-sensitive <a href="http://www.w3.org/TR/CSS21/syndata.html#value-def-identifier">CSS identifier</a> [[!CSS21]].

   588   It <i>matches</i> pages of the <a href="#using-named-pages">named page type</a>

   589   generated by the 'page' property.

   590   <span id="page-selector-syntax-restrict">

   591     A page type name of ''auto''

   592     (<a href="http://www.w3.org/TR/CSS21/syndata.html#characters">ASCII case-insensitive</a>)

   593     does not make the rule invalid,

   594     but <em class="RFC2119">MUST</em> never match.

   595   </span>

   597   <p>A <dfn>page pseudo-class</dfn> is <a href="http://www.w3.org/TR/CSS21/syndata.html#characters">ASCII case-insensitive</a>

   598   and has the same syntax as <a href="http://www.w3.org/TR/selectors/#pseudo-classes">pseudo-classes</a> in regular Selectors. [[!SELECT]]

   599   The various <i>page pseudo-classes</i> are defined below.

   601 <h4 id="spread-pseudos"><a id="left-right-first"></a>

   602 Spread pseudo-classes: '':left'', '':right''</h4>

   604   <p>When printing double-sided documents,

   605   left and right pages are often formatted differently.

   606   This can be expressed by using the '':left'' and '':right'' page pseudo-classes.

   608   <p>All pages are automatically classified by user agents

   609   as either left pages or right pages,

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

   611   The <dfn>'':left''</dfn> and <dfn>'':right''</dfn> pseudo-classes

   612   only <i>match</i> <i title="left page">left</i> or <i title="right page">right pages</i>,

   613   respectively.

   615 <div class="example">

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

   617 <pre>

   618 @page :left {

   619 margin-left: 3cm;

   620 margin-right: 4cm;

   621 }

   623 @page :right {

   624 margin-left: 4cm;

   625 margin-right: 3cm;

   626 }

   627 </pre>

   628 </div>

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

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

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

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

   634 correctly formatted output).</p>

   636 <div class="note">

   637 <p>

   638   <em><strong>Note.</strong>

   639   Adding declarations to the '':left'' or '':right'' pseudo-class

   640   does not necessarily influence whether the document

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

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

   643 </p>

   644 </div>

   646 <h4 id="first-pseudo">

   647 First-page pseudo-class: '':first''</h4>

   649   <p>The <dfn>'':first''</dfn> pseudo-class <i title="match">matches</i>

   650   the first printed page of a document.

   652 <div class="example">

   653 <pre>

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

   656 @page :first {

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

   658 }

   659 </pre>

   660 </div>

   662 <h4 id="blank-pseudo">

   663 Blank-page pseudo-class: '':blank''</h4>

   665   <p>The <dfn>'':blank''</dfn> pseudo-class <i title="match">matches</i>

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

   667   that appear as a result of

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

   670   <div class="note">

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

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

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

   674   </div>

   676 <div class="example">

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

   678 <pre>

   679 h1 { break-before: left }

   681 @page :blank {

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

   683 }

   684 </pre>

   685 </div>

   687 <p>

   688   A page matched by '':blank'' can also be matched

   689   by other page pseudo-classes.

   691 <div class="example">

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

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

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

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

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

   698 while the page number remains:

   700 <pre>

   701 h1 { break-before: left }

   703 @page :blank {

   704   @top-center { content: none }

   705 }

   707 @page :right {

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

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

   710 }

   711 </pre>

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

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

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

   716 edition"</code>.

   718 </div>

   720 <div class="note">

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

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

   723 </div>

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

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

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

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

   730 to the following grammar:</p>

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

   733 productions:</p>

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

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

   736 <pre class="lexical">

   737 PAGE_SYM              ::= "@page"

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

   739 TOPLEFT_SYM           ::= "@top-left"

   740 TOPCENTER_SYM         ::= "@top-center"

   741 TOPRIGHT_SYM          ::= "@top-right"

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

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

   744 BOTTOMLEFT_SYM        ::= "@bottom-left"

   745 BOTTOMCENTER_SYM      ::= "@bottom-center"

   746 BOTTOMRIGHT_SYM       ::= "@bottom-right"

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

   748 LEFTTOP_SYM           ::= "@left-top"

   749 LEFTMIDDLE_SYM        ::= "@left-middle"

   750 LEFTBOTTOM_SYM        ::= "@left-bottom"

   751 RIGHTTOP_SYM          ::= "@right-top"

   752 RIGHTMIDDLE_SYM       ::= "@right-middle"

   753 RIGHTBOTTOM_SYM       ::= "@right-bottom"

   755 <dfn>media</dfn> :

   756      MEDIA_SYM S* medium [ COMMA S* medium ]* LBRACE S* [ <i>page_rule</i> | ruleset ]* '}' S*

   757      ;

   759 <dfn id="syntax-prod-page">page_rule</dfn> :

   760      PAGE_SYM S* <i>page_selector_list</i> '{' S* <i>page_body</i> '}' S*

   761      ;

   763 <dfn>page_selector_list</dfn> :

   764      [ <i>page_selector</i> S* [ ',' <i>page_selector</i> S* ]* ]?

   765      ;

   767 <dfn>page_selector</dfn> :

   768      <i>pseudo_page</i>+ | IDENT <i>pseudo_page</i>*

   769      ;

   771 <dfn id="syntax-prod-pseudo-page">pseudo_page</dfn> :

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

   773      ;

   775 <dfn>page_body</dfn> :  /* Can be empty */

   776      declaration? [ ';' S* <i>page_body</i> ]? |

   777      <i>page_margin_box</i> <i>page_body</i>

   778      ;

   780 <dfn id="syntax-prod-margin">page_margin_box</dfn> :

   781      <i>margin_sym</i> S* '{' S* declaration? [ ';' S* declaration? ]* '}' S*

   782      ;

   784 <dfn id="syntax-prod-margin-sym">margin_sym</dfn> :

   785      TOPLEFTCORNER_SYM |

   786      TOPLEFT_SYM |

   787      TOPCENTER_SYM |

   788      TOPRIGHT_SYM |

   789      TOPRIGHTCORNER_SYM |

   790      BOTTOMLEFTCORNER_SYM |

   791      BOTTOMLEFT_SYM |

   792      BOTTOMCENTER_SYM |

   793      BOTTOMRIGHT_SYM |

   794      BOTTOMRIGHTCORNER_SYM |

   795      LEFTTOP_SYM |

   796      LEFTMIDDLE_SYM |

   797      LEFTBOTTOM_SYM |

   798      RIGHTTOP_SYM |

   799      RIGHTMIDDLE_SYM |

   800      RIGHTBOTTOM_SYM

   801      ;

   802 </pre>

   804 <div class="example">

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

   806 left blank)</p>

   807 <pre>

   808 @page { ... }

   809 @page :left { ... }

   810 @page :right { ... }

   811 @page LandscapeTable { ... }

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

   813 @page:first { ... }

   814 @page toc, index { ... }

   815 @page :blank:first { ... }

   816 </pre>

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

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

   820 <pre>

   821 @page {

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

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

   824 }

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

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

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

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

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

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

   832 </pre>

   833 </div>

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

   837 <p>Declarations in page and margin contexts <a href="http://www.w3.org/TR/CSS21/cascade.html">cascade</a> just like declarations in style rule for elements.</p>

   839 <p>The <dfn>specificity</dfn> of page a selector is computed in a manner

   840 analogous to the computations defined in

   841 the <a href="http://www.w3.org/TR/CSS21/selector.html">Selectors</a> module:

   843 <ul>

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

   845     <p class="note">

   846       Given the syntax of page seletors, <var>f</var> can only ever be 0 or 1.

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

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

   849 </ul>

   851 <p class="note">

   852   Note: Repeated occurrences of the same pseudo-classes are allowed

   853   and do increase specificity.

   855 <p>

   856   Due to storage limitations,

   857   implementations may have limitations on

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

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

   860   and not overflow.

   862 <p>

   863   Specificities are compared by comparing the three components in order

   864   (<var>f</var>, <var>g</var>, <var>h</var>):

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

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

   867   then the two <var>g</var> values are compared, etc.

   868   If all the values are tied, the two specificities are equal.

   870 <div class="example">

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

   873 <pre>

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

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

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

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

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

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

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

   881 </pre>

   882 </div>

   884 <div class="example">

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

   887 <pre>

   888 @page :left {

   889   margin-left: 4cm;

   890 }

   892 @page {

   893   margin-left: 3cm;

   894 }

   895 </pre>

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

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

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

   900 </div>

   902 <div class="example">

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

   904 rule.

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

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

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

   908 <pre>

   909 @page :first {

   910   color: green;

   912   @top-left {

   913     content: "foo";

   914     color: blue;

   915   }

   916   @top-right {

   917     content: "bar";

   918   }

   919 }

   921 @page { color: red;

   922   @top-center {

   923     content: "Page " counter(page);

   924   }

   925 }

   926 </pre>

   927 </div>

   929 <div class="example">

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

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

   933 <pre>

   934 @page { margin: 25mm;}

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

   936 </pre>

   937 </div>

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

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

   942   like pseudo-elements, can contain generated content.

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

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

   946   such as the page number or document title.

   948   <div class="example">

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

   950     in documents with a predominately horizontal writing direction

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

   952     for documents with a predominately vertical writing direction.

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

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

   955     page-margin boxes.

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

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

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

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

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

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

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

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

   965     at the top of the page could use the

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

   967     page-margin boxes as the page footer.

   968     The design of a vertically written document could use

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

   970   </div>

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

   973   and are independent of page orientation,

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

   975   in both portrait and landscape orientation.

   976   The various page-margin boxes are defined

   977   and illustrated in the diagram below:

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

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

   981     <thead>

   982       <tr>

   983         <th>Box</th>

   984         <th>Description</th>

   985         <th>Placement</th>

   986       </tr>

   987     </thead>

   988     <tbody>

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

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

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

   992         page box</td>

   993         <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"

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

   995       </tr>

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

   997         <th>top-left</th>

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

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

  1000         <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"

  1001         height="47" width="181"></td>

  1002       </tr>

  1003       <tr id="top-center-box-def">

  1004         <th>top-center</th>

  1005         <td>a variable-width box centered horizontally between the page's left and right

  1006         border edges and filling the page top margin between the top-left and top-right

  1007         page-margin boxes</td>

  1008         <td><img src="TopCenterMarginBox.png" alt="the top center box with margin, border, and padding, centered within the page's top margin"

  1009         height="47" width="181"></td>

  1010       </tr>

  1011       <tr id="top-right-box-def">

  1012         <th>top-right</th>

  1013         <td>a variable-width box filling the top page margin between the top-center and

  1014         top-right-corner page-margin boxes</td>

  1015         <td><img src="TopRightMarginBox.png" alt="the top right box with margin, border, and padding, nested within the page's top margin"

  1016         height="47" width="181"></td>

  1017       </tr>

  1018       <tr>

  1019         <th id="top-right-corner-box-def">top-right-corner</th>

  1020         <td>a fixed-size box defined by the intersection of the top and right margins of

  1021         the page box</td>

  1022         <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"

  1023         height="47" width="181"></td>

  1024       </tr>

  1025       <tr id="left-margin-boxes-def">

  1026         <th id="left-top-box-def">left-top</th>

  1027         <td>a variable-height box filling the left page margin between the top-left-corner

  1028         and left-middle page-margin boxes</td>

  1029         <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"

  1030         height="226" width="181"></td>

  1031       </tr>

  1032       <tr id="left-middle-box-def">

  1033         <th>left-middle</th>

  1034         <td>a variable-height box centered vertically between the page's top and bottom

  1035         border edges and filling the left page margin between the left-top and

  1036         left-bottom page-margin boxes</td>

  1037       </tr>

  1038       <tr id="left-bottom-box-def">

  1039         <th>left-bottom</th>

  1040         <td>a variable-height box filling the left page margin between the left-middle and

  1041         bottom-left-corner page-margin boxes</td>

  1042       </tr>

  1043       <tr id="right-margin-boxes-def">

  1044         <th id="right-top-box-def">right-top</th>

  1045         <td>a variable-height box filling the right page margin between the

  1046         top-right-corner and right-middle page-margin boxes</td>

  1047         <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"

  1048         height="226" width="181"></td>

  1049       </tr>

  1050       <tr id="right-middle-box-def">

  1051         <th>right-middle</th>

  1052         <td>a variable-height box centered vertically between the page's top and bottom

  1053         border edges and filling the right page margin between the right-top and

  1054         right-bottom page-margin boxes</td>

  1055       </tr>

  1056       <tr id="right-bottom-box-def">

  1057         <th>right-bottom</th>

  1058         <td>a variable-height box filling the right page margin between the right-middle

  1059         and bottom-right-corner page-margin boxes</td>

  1060       </tr>

  1061       <tr id="bottom-margin-boxes-def">

  1062         <th id="bottom-left-corner-box-def">bottom-left-corner</th>

  1063         <td>a fixed-size box defined by the intersection of the bottom and left margins of

  1064         the page box</td>

  1065         <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"

  1066         height="48" width="181"></td>

  1067       </tr>

  1068       <tr id="bottom-left-box-def">

  1069         <th>bottom-left</th>

  1070         <td>a variable-width box filling the bottom page margin between the

  1071         bottom-left-corner and bottom-center page-margin boxes</td>

  1072         <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"

  1073         height="48" width="181"></td>

  1074       </tr>

  1075       <tr id="bottom-center-box-def">

  1076         <th>bottom-center</th>

  1077         <td>a variable-width box centered horizontally between the page's left and right

  1078         border edges and filling the bottom page margin between the bottom-left and

  1079         bottom-right page-margin boxes</td>

  1080         <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"

  1081         height="48" width="181"></td>

  1082       </tr>

  1083       <tr id="bottom-right-box-def">

  1084         <th>bottom-right</th>

  1085         <td>a variable-width box filling the bottom page margin between the bottom-center

  1086         and bottom-right-corner page-margin boxes</td>

  1087         <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"

  1088         height="48" width="181"></td>

  1089       </tr>

  1090       <tr id="bottom-right-corner-box-def">

  1091         <th>bottom-right-corner</th>

  1092         <td>a fixed-size box defined by the intersection of the bottom and right margins of

  1093         the page box</td>

  1094         <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"

  1095         height="48" width="181"></td>

  1096       </tr>

  1097     </tbody>

  1098   </table>

  1100 <h3 id="margin-at-rules">At-rules for page-margin boxes</h3>

  1102 <p>Page-margin boxes are created by

  1103 <a href="#margin-at-rules">margin at-rules</a>

  1104 inside the <a href="#page-context">page context</a>.

  1105 Authors should put these rules after any declarations in the page context

  1106 as legacy clients may not handle declarations

  1107 after margin at-rules correctly.

  1108 </p>

  1110 <p>A <dfn id="margin-at-rule">margin at-rule</dfn> consists of an

  1111 <a href="#specializatons-of-ATKEYWORD">ATKEYWORD</a>

  1112 that identifies the page-margin box

  1113 (e.g. <span class="css">'@top-left'</span>) and a block of declarations (said

  1114 to be in the <dfn id="margin-context">margin context</dfn>).</p>

  1116 <div class="example">

  1118 <p>The following style sheet establishes a page header containing the title

  1119 ("Hamlet") on the left side and the page number, preceded by "Page ", on the

  1120 right side:</p>

  1121 <pre>

  1122 @page {

  1123   size: 8.5in 11in;

  1124   margin: 10%;

  1126   @top-left {

  1127     content: "Hamlet";

  1128   }

  1129   @top-right {

  1130     content: "Page " counter(page);

  1131   }

  1132 }

  1133 </pre>

  1134 </div>

  1137 <h3 id="populating-margin-boxes">Populating page-margin boxes</h3>

  1139 <p>As with the '':before'' and '':after'' pseudo-elements,

  1140 a specified 'content: normal' on a page-margin box computes to ''none''.

  1141 A page-margin box is <dfn>generated</dfn>

  1142 if and only if the computed value of its 'content' property is not 'none'.

  1143 Otherwise, no box is generated, as for elements with ''display: none''.

  1145 <p class=note>

  1146   The 'display' property does not apply to page-margin boxes.

  1148 <div class="example">

  1149 <p>The following style sheet creates a green box in each corner of the page

  1150 except the bottom-left corner.</p>

  1151 <pre>

  1152   @page {

  1153     @top-left-corner { content: " "; border: solid green; }

  1154     @top-right-corner { content: url(foo.png); border: solid green; }

  1155     @bottom-right-corner { content: counter(page); border: solid green; }

  1156     @bottom-left-corner { content: normal; border: solid green; }

  1157   }

  1158 </pre>

  1159 </div>

  1161 <h3 id="margin-dimension">Computing Page-margin Box Dimensions</h3>

  1163 <p>The width and height of each page-margin box is determined by the rules

  1164 below. These rules define the equivalent of CSS2.1 Sections 10.3 and

  1165 10.6 for page-margin boxes.</p>

  1167 <p>The rules for applying 'min-height', 'max-height', 'min-width', and

  1168 'max-width' [[!CSS21]] do apply to page-margin boxes and may imply

  1169 a recalculation of the width, height, and/or margins

  1170 if the dimensions resulting from the specified 'width' or 'height'

  1171 violate their constraints.

  1172 If the UA does not support the 'min-height' or 'min-width' properties

  1173 then it must behave as if 'min-height' and 'min-width' were always zero.

  1175 <h4 id="margin-box-terms"><a id="max-margin-dimension"></a>Page-Margin Box Layout Terminology</h4>

  1177   <p>In addition to the box model definitions in CSS2.1 [[!CSS21]],

  1178   and the sizing terms in CSS Intrinsic Sizing [[!CSS3-SIZING]],

  1179   the following terms are defined for use

  1180   in the subsequent page-margin box calculations:

  1182   <dl>

  1184     <dt><dfn>available width</dfn></dt>

  1185     <dd>The sum of the page’s

  1186       left border width, left padding, <a href="#page-box">page area</a> width,

  1187       right padding, and right border width.

  1188       In other words, it is the distance between

  1189       the <a href="#page-box">page box</a>’s left right border edges.

  1190       This quantity is used  when calculating dimensions

  1191       of the top and bottom page-margin boxes.

  1193     <dt><dfn>available height</dfn></dt>

  1194     <dd>The sum of the page’s

  1195       top border width, top padding, <a href="#page-box">page area</a> height,

  1196       bottom padding, and bottom border width.

  1197       In other words, it is the distance between

  1198       the <a href="#page-box">page box</a>’s top bottom border edges.

  1199       This quantity is used when calculating dimensions

  1200       of the left and right page-margin boxes.

  1202     <dt><dfn>outer width</dfn></dt>

  1203     <dd>The width of the

  1204       <a href="http://www.w3.org/TR/CSS21/box.html#outer-edge">outer edge</a>,

  1205       as defined in [[!CSS21]].

  1207     <dt><dfn>outer min width</dfn></dt>

  1208     <dd>Like the <i>outer width</i>, except that

  1209     <a href="http://www.w3.org/TR/css3-sizing/#min-content">''min-content''</a>

  1210     is used when the width is ''auto''.

  1212     <dt><dfn>outer max width</dfn></dt>

  1213     <dd>Like the <i>outer width</i>, except that

  1214     <a href="http://www.w3.org/TR/css3-sizing/#max-content">''max-content''</a>

  1215     is used when 'width' is ''auto''.

  1216   </dl>

  1218   <p>The <dfn>containing block</dfn> for a corner page-margin box is

  1219   the rectangle defined by the intersection of the two page margins meeting at that corner.

  1221   <p>For all other page-margin boxes,

  1222   the <dfn>containing block</dfn> is the rectangle

  1223   formed by the encapsulating page margin minus the containing blocks of the

  1224   adjacent corners' page-margin boxes.

  1225   This means that the size of this containing block is given

  1226   in one dimension by the used page margin and in the other dimension

  1227   by the <i>available width</i>

  1228   (for top and bottom page-margin boxes) or

  1229   <i>available height</i>

  1230   (for left and right page-margin boxes).</p>

  1232 <h4 id="variable-sizing">

  1233 Page-Margin Box Variable Dimension Computation Rules</h4>

  1235 <p>The following rules apply to 'top-left', 'top-center' and 'top-right'

  1236 page-margin boxes,

  1237 which are referred to as A, B, and C, respectively, in this section.</p>

  1239 <h5 id="variable-auto-margins">Margins</h5>

  1241 <p>If the 'margin-left' or 'margin-right' property of any of the three boxes

  1242 computes to ''auto'', the used value is zero.</p>

  1244 <h5 id="variable-auto-sizing">Resolving ''auto'' widths</h5>

  1246 <p>The following algorithm determines the used width of each box.

  1247 For this purpose, boxes that are not <i>generated</i>

  1248 are assumed to have a 'width' and an <i>outer width</i> of zero.

  1249 </p>

  1251 <p class="note">

  1252 Note: The high-level goals are (in order of priority) to center the middle

  1253 box (B) if it is generated, to minimize overflow and overlap, and to

  1254 distribute space proportionally to the amount of content.</p>

  1256   <p>If the middle box (B) is not <i>generated</i>,

  1257   distribute the <i>available width</i> to A and C as follows:

  1259   <ul>

  1260     <li>

  1261       If only one box has 'width: auto',

  1262       its used width is resolved so that

  1263       the sum of the <i>outer width</i>s equals <i>available width</i>.

  1264     </li>

  1266     <li id="flex-fit">

  1267       If A and C both have 'width: auto', distribute the space to each box as follows:

  1268       <ol>

  1269         <li>If the sum of the outer <i>max-content widths</i> is less than the <i>available width</i>,

  1270             call that difference the <i>flex space</i>.

  1271             Calculate each box's <i>flex factor</i> as proportional to

  1272             its outer <i>max-content width</i>,

  1273             and set its used outer width to:

  1274             <p><code><i>max-content width</i> + <i>flex space</i> × <i>flex factor</i> ÷ ∑<i>flex factors</i></code></p>

  1275         <li>Otherwise if the sum of the outer <i>min-content widths</i> is less than the <i>available width</i>,

  1276             call that difference the <i>flex space</i>

  1277             calculate each box's <i>flex factor</i> as proportional to

  1278             its <i>max-content</i> minus <i>min-content</i>,

  1279             and set its used outer width to:

  1280             <p><code><i>min-content width</i> + <i>flex space</i> × <i>flex factor</i> ÷ ∑<i>flex factors</i></code></p>

  1281         <li>Otherwise,

  1282             calculate its outer size as in the previous case,

  1283             but set each box's <i>flex factor</i> as proportional to

  1284             its outer <i>min-content width</i>.

  1285       </ol>

  1286       In each case, both <i>flex factors</i> are assumed to be ''1'' if their sum is equal to zero.

  1287     </li>

  1288   </ul>

  1290   <p>If the middle box (B) is <i>generated</i>,

  1291   determine the ''auto'' widths of A, B, and C as follows:

  1293   <ol>

  1294     <li>

  1295       First, resolve any ''auto'' width of the middle box (B):

  1296       Assume there are two boxes, B and AC,

  1297       where each of AC's dimensions is double the maximum of A and C.

  1298       (This preserves B's centering.)

  1299       Distribute the space to these two boxes (B and the imaginary AC)

  1300       as described for A and C <a href="#flex-fit">above</a>.

  1301     <li>

  1302       Then, resolve any ''auto'' widths of the side boxes (A and C)

  1303       by setting that box's outer width to

  1304       <p><code>(<i>available width</i> &minus; <i>used outer size of B</i>) ÷ 2</code></p>

  1305     </li>

  1306   </ol>

  1308 <h5 id="variable-minmax">Handling 'min-width' and 'max-width'</h5>

  1310 <p>

  1311   The 'min-width' and 'max-width' properties [[CSS21]] apply to page-margin

  1312   boxes in the variable dimension like on normal elements, except that the

  1313   three boxes on the same side are considered together.

  1314 </p>

  1316 <p>

  1317   More precisely:

  1318 </p>

  1320 <ol>

  1321   <li>

  1322     The tentative used widths are calculated

  1323     (without 'min-width' and 'max-width') following the rules under

  1324     <a href="#variable-auto-sizing">Resolving ''auto'' widths</a>

  1325     above.

  1326   </li>

  1327   <li>

  1328     If the tentative used width of any of the three boxes

  1329     is greater than 'max-width', the rules above are applied again,

  1330     but this time using the computed value of 'max-width'

  1331     as the computed value for 'width'.

  1332   </li>

  1333   <li>

  1334     If the resulting width of any of the three boxes

  1335     is smaller than 'min-width', the rules above are applied again,

  1336     but this time using the value of 'min-width'

  1337     as the computed value for 'width'.

  1338   </li>

  1339 </ol>

  1341 <h5 id="variable-position">Positioning</h5>

  1343 <p>

  1344   Once the dimensions of the boxes are determined,

  1345   they are positioned as follows:

  1346 </p>

  1348 <ul>

  1349   <li>The left outer edge of A is flush with the left edge of the

  1350       containing block</li>

  1351   <li>The outer area of B is centered in the containing block.</li>

  1352   <li>The right outer edge of C is flush with the right edge of the

  1353       containing block.</li>

  1354 </ul>

  1356 <h5 id="variable-mapping">Boxes on other sides</h5>

  1358 <p>The used values for 'bottom-left', 'bottom-center' and 'bottom-right'

  1359 page-margin boxes are established by the same rules as

  1360 for 'top-left', 'top-center', and 'top-right', respectively.</p>

  1362 <p>The used values for 'left-top', 'left-middle' and 'left-bottom' boxes are

  1363 established by the same rules, with "width" replaced by "height", "left" by

  1364 "top", "right" by "bottom" and "center" by "middle".</p>

  1366 <p>The used values for 'right-top', 'right-middle' and 'right-bottom'

  1367 page-margin boxes

  1368 are established by the same rules as for 'left-top', 'left-middle' and

  1369 'left-bottom', respectively.</p>

  1371 <h4 id="fixed-sizing">Page-Margin Box Fixed Dimension Computation Rules</h4>

  1373 <p>The rules below are used to calculate the used values of each

  1374 'top-left-corner', 'top-left', 'top-center', 'top-right', and

  1375 'top-right-corner' page-margin box's 'height', 'margin-top', and 'margin-bottom'

  1376 properties:</p>

  1378 <ol>

  1379   <li>The following constraint must hold among the used values of the margin

  1380   box's properties:

  1381   <p>'margin-top' + 'border-top-width' + 'padding-top' + 'height' +

  1382   'padding-bottom' + 'border-bottom-width' + 'margin-bottom' = top page margin

  1384   <li>If 'border-top-width' + 'padding-top' + 'height' (if it is not ''auto'')

  1385   + 'padding-bottom' + 'border-bottom-width', plus 'margin-top' and/or

  1386   'margin-bottom' if not ''auto'', is larger than the height of the top page

  1387   margin, then any ''auto'' values for 'margin-top' or 'margin-bottom' are, for

  1388   the following rules, treated as zero.

  1390   <li>If at this point all of 'height', 'margin-top', and 'margin-bottom'

  1391   have a computed value other than ''auto'', the values are said to be

  1392   "over-constrained". In this case, the specified value of 'margin-top' is

  1393   treated as 'auto'.

  1395   <li>If there is now exactly one value specified as 'auto', its used value

  1396   follows from the equality.

  1398   <li>If 'height' is set to 'auto', any other 'auto' values become '0' and

  1399   'height' follows from the resulting equality

  1401   <li>If both 'margin-top' and 'margin-bottom' are 'auto',

  1402   their used values are equal.

  1403   This vertically centers the page-margin box content

  1404   within the top page margin.

  1405 </ol>

  1407 <p>The same rules apply to the bottom page-margin boxes (bottom-left-corner,

  1408 bottom-left, bottom-center, bottom-right, and bottom-right-corner), except that

  1409 in the overconstrained case, the 'margin-bottom' is ignored rather than the

  1410 'margin-top'.</p>

  1412 <p>Analogous rules govern the properties for the left and right

  1413 page-margin boxes with respect to 'width'

  1414 (top-left-corner, left-top, left-middle, left-bottom, and

  1415 bottom-left-corner; top-right-corner, right-top, right-middle, right-bottom,

  1416 bottom-right-corner), with 'top' replaced by 'left', 'bottom' replaced by

  1417 'right', and 'height' replaced by 'width'.

  1418 In the overconstrained case for left (right) page-margin boxes,

  1419 the specified value of 'margin-left' ('margin-right') is ignored.</p>

  1421 <h3 id="margin-box-ex">Page-margin box examples</h3>

  1423 <p>The following is a collection of examples of page-margin box usage.</p>

  1425 <div class="example">

  1427 <p>Here is an example of a page with only a top-left header:</p>

  1428 <pre>

  1429 @page {

  1430 @top-left { content: "Header in Left Cell (top-left)" }

  1431 }

  1432 </pre>

  1434 <p>Because there are no contents defined for the top-center or the top-right

  1435 page-margin boxes, the extent of the top-left page-margin box

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

  1438 <p><img alt="Header Example 1" src="header-ex-1.png" height="177" width="737"></p>

  1439 </div>

  1441 <div class="example">

  1443 <p>The following is an example of a page with a centered header:</p>

  1444 <pre>

  1445 @page {

  1446 @top-center { content: "Header in Center Cell (top-center)" }

  1447 }

  1448 </pre>

  1450 <p><img alt="Header Example 2" src="header-ex-2.png" height="177" width="737"></p>

  1451 </div>

  1453 <div class="example">

  1455 <p>The following is an example of a page with a single header in the top-right

  1456 page-margin box:</p>

  1457 <pre>

  1458 @page {

  1459 @top-right { content: "Header in Right Cell (top-right)" }

  1460 }

  1461 </pre>

  1463 <p>Because the content of the center cell is empty, the extent of the top-right

  1464 page-margin box is allowed to cross the center of the page box.</p>

  1466 <p><img alt="Header Example 3" src="header-ex-3.png" height="177" width="737"></p>

  1467 </div>

  1469 <div class="example">

  1471 <p>The following is an example of a page with a top-center and a top-left header:</p>

  1472 <pre>

  1473 @page {

  1474 @top-left { content: "Left Cell (top-left)" }

  1475 @top-center { content: "Header in Center Cell (top-center)" }

  1476 }

  1477 </pre>

  1479 <p><img alt="Header Example 4" src="header-ex-4.png" height="177" width="737"></p>

  1480 </div>

  1482 <div class="example">

  1484 <p>The following is an example of a page with a top-center and a top-right header:</p>

  1485 <pre>

  1486 @page {

  1487 @top-center { content: "Header in Center Cell (top-center)" }

  1488 @top-right { content: "Right Cell (top-right)" }

  1489 }

  1490 </pre>

  1492 <p><img alt="Header Example 5" src="header-ex-5.png" height="177" width="737"></p>

  1493 </div>

  1495 <div class="example">

  1497 <p>The following is an example of a page with top-left and top-right headers:</p>

  1498 <pre>

  1499 @page {

  1500 @top-left { content: "Header in top-left with approx. "

  1501                    "twice as many words as right cell." }

  1502 @top-right { content: "Right cell (top-right)" }

  1503 }

  1504 </pre>

  1506 <p>Because there are no center cell contents, the extent of the top-left is

  1507 allowed to cross the center of the page box.</p>

  1509 <p><img alt="Header Example 6" src="header-ex-6.png" height="177" width="737"></p>

  1510 </div>

  1512 <h2 id="page-properties">Page Properties</h2>

  1513 <div>

  1515 <p>

  1516   <a href="#properties-list">Appendix A</a> defines the normative list of

  1517   CSS 2.1 [[!CSS21]]

  1518   <a href="#page-property-list">properties that apply to page boxes</a>.

  1519   If a conforming user agent supports any of these properties on block boxes,

  1520   then it <em class="RFC2119">MUST</em> also support that property

  1521   in the <i>page context</i>.

  1522   This specification additionally defines the 'size' property

  1523   that only applies in the page context.

  1525 <p>

  1526   Properties that apply to the page-margin boxes can also be set

  1527   within the page context:

  1528   if inheritable or explicitly inherited

  1529   (with the ''inherit'' keyword in the margin context),

  1530   they will inherit to the page-margin boxes.

  1532 <p>

  1533   The same appendix defines the normative list of

  1534   CSS 2.1 [[!CSS21]]

  1535   <a href="#page-property-list">properties that apply to page-margin boxes</a>.

  1536   If a conforming user agent supports any of these properties on block boxes,

  1537   then it <em class="RFC2119">MUST</em> also support that property

  1538   in the <i>margin context</i>.

  1540 <p>

  1541   Other properties defined by [[!CSS21]] do not apply in these contexts.

  1542   Behavior for properties not included in CSS 2.1 is undefined.

  1544 <p class="note">

  1545 Note: The intent of leaving other properties undefined is to allow the gradual

  1546 addition of appropriate CSS3 properties as they emerge, without having to

  1547 update this specification with each addition.</p>

  1549 <p><a href="http://www.w3.org/TR/CSS21/cascade.html#value-stages">As with

  1550 elements in the document</a>, both the page context and the margin context

  1551 have a computed value for every property, even if that property does not

  1552 apply to the page or page-margin box.</p>

  1554 <p>The normal rules for CSS properties apply with the following exceptions:</p>

  1556 <ul>

  1557   <li>page-margin boxes inherit from the page context.

  1558   The page context inherits from the root element.

  1559   However, since the previous revision of CSS Paged

  1560   Media Level 3 did not specify this point, an implementation that sets

  1561   inherited properties in the page context to their initial values (as for the

  1562   root element) is also conformant to CSS Paged Media Level 3. Note that this

  1563   exception will be removed in Level 4.

  1564   <li>Values in units of ''em'' and ''ex'' are interpreted relative to the font

  1565   associated with their context. When used on the 'font-size' property in the

  1566   margin context, they are relative to the font of the page context. When used

  1567   on the 'font-size' property in the page context, they are relative to the

  1568   'font-size' of the root element. However, since a previous revision of CSS

  1569   Paged Media Level 3 was ambiguous on this point, an implementation that

  1570   treats ''em'' and ''ex'' on 'font-size' as relative to the initial value is

  1571   also conformant to CSS Paged Media Level 3. Note that this exception will

  1572   be removed in Level 4.

  1573   <li>Percentage values on the margin and padding properties are relative to the

  1574   dimensions of the containing block. For right and left values, percentages are

  1575   relative to the width of the containing block; for top and bottom values,

  1576   percentages are relative to the height of the containing block.</li>

  1577   <li>The used values of 'width' and 'height' have special computation rules

  1578   for page boxes and page-margin boxes; see <a href="#page-size">Page Size</a>

  1579   and <a href="#margin-dimension">Computing Page-Margin Box Dimensions</a>.

  1580   <li>The page background is positioned and painted

  1581     <a href="#painting">as described above</a>.

  1582   <li>The rules for counter scoping are modified <a href="#page-based-counters">as

  1583   described below</a>.</li>

  1584   <li>

  1585     As on the '::before' and '::after' pseudo-elements,

  1586     the ''normal'' value of the 'content' property computes to ''none''

  1587     on page-margin boxes.

  1588   </li>

  1589   <li>On page-margin boxes, the 'vertical-align' property behaves

  1590   <a href="http://www.w3.org/TR/CSS21/tables.html#height-layout">as specified for table cells</a>.

  1591   It <em>always</em> performs alignment in the vertical dimension,

  1592   regardless of writing mode.

  1593 </ul>

  1595 <p>It is <em class="RFC2119">recommended</em> that user agents establish a default

  1596 page margin via the user agent stylesheet that includes any non-printable area.

  1597 It is further <em class="RFC2119">recommended</em> that authors assume that the

  1598 default page area will not include unprintable regions.</p>

  1600 <h3 id="page-based-counters">Page-based counters</h3>

  1602 <p>Counters can be defined and controlled within an <span class="css">'@page'</span>

  1603 rule, and used as content in page-margin boxes.

  1604 This is useful for maintaining a page count.</p>

  1606 <p>A 'counter-increment' within either a page or margin context causes the counter

  1607 to increment with the generation of each page box.</p>

  1609 <p>If a counter is reset or incremented within the page context, it is in scope

  1610 for all page-margin boxes and obscures all counters of the same name within the

  1611 document.</p>

  1613 <p>If a counter is reset or incremented within a margin context, it is in scope

  1614 for that page-margin box and obscures any counters of the same name

  1615 in both the page context and the document.</p>

  1617 <p>If a counter that has not been reset or incremented within the margin context

  1618 or the page context is used by counter() or counters() in the margin context,

  1619 then the resultant value is exactly

  1620 as if the page-margin box were an element within

  1621 the document at the start of the page, inside the deepest element in the normal

  1622 flow that spans the page break. Use of the counter in this way does not affect

  1623 the calculation of the counter's value.</p>

  1625 <p>

  1626   A counter named ''page'' is automatically created

  1627   and incremented by 1 on every page of the document,

  1628   unless the 'counter-increment' property in the <i>page context</i>

  1629   explicitly specifies a different increment for the ''page'' counter.

  1630   The implied ''page'' counter is a real counter,

  1631   and can be directly affected using the 'counter-increment' and 'counter-reset' properties

  1632   when named explicitly in those properties.

  1633   It can also be used in the 'counter()' and 'counters()' function forms.

  1634 </p>

  1636 <div class="example">

  1637 <p>The following rules result in the placement of the current page number in the

  1638 middle of the outside margin of each page.</p>

  1639 <pre>

  1640 @page {

  1641   margin: 10%;

  1643   @top-center {

  1644     font-family: sans-serif;

  1645     font-weight: bold;

  1646     font-size: 2em;

  1647     content: counter(page);

  1648   }

  1649 }

  1650 </pre>

  1652 <p>Adding the following rule will make all pages even-numbered.</p>

  1653 <pre>

  1654 @page {

  1655   counter-increment: page 2;

  1656 }

  1657 </pre>

  1658 </div>

  1660 <p>Additionally, a counter named ''pages'' is automatically created by the UA.

  1661 Its value is always the total number of pages in the document. (In continuous

  1662 media this is always 1.) The value of ''pages'' cannot be manipulated: while

  1663 'counter-reset' and 'counter-increment' statements that set it are valid, they

  1664 have no effect.

  1666   <p>In all other respects, page-associated counters behave as described

  1667     in [[!CSS21]],

  1668     <a href="http://www.w3.org/TR/CSS21/generate.html#scope">Nested Counters

  1669     and Scope</a> and

  1670     <a href="http://www.w3.org/TR/CSS21/syndata.html#counter">Counters</a>.

  1672 <h3 id="margin-text-alignment">Page-margin boxes and default values</h3>

  1674 <p>Properties used within page or margin contexts take their initial values from

  1675 their respective property definitions; however, user agents must behave as

  1676 though the values in the following table were established by rules in the UA

  1677 default style sheet.</p>

  1678 <table id="margin-values" class="data" summary="definition of page-margin box default properties">

  1679   <caption>Table 2. Default values for Page-Margin Boxes</caption>

  1680   <thead>

  1681     <tr>

  1682       <th>Page-margin box</th>

  1683       <th><span class="property">'text-align'</span></th>

  1684       <th><span class="property">'vertical-align'</span></th>

  1685     </tr>

  1686   </thead>

  1687   <tbody>

  1688     <tr>

  1689       <td><a href="#top-left-corner-box-def">top-left-corner</a></td>

  1690       <td>right</td>

  1691       <td>middle</td>

  1692       </tr>

  1693     <tr>

  1694       <td><a href="#top-left-box-def">top-left</a></td>

  1695       <td>left</td>

  1696       <td>middle</td>

  1697       </tr>

  1698     <tr>

  1699       <td><a href="#top-center-box-def">top-center</a></td>

  1700       <td>center</td>

  1701       <td>middle</td>

  1702       </tr>

  1703     <tr>

  1704       <td><a href="#top-right-box-def">top-right</a></td>

  1705       <td>right</td>

  1706       <td>middle</td>

  1707       </tr>

  1708     <tr>

  1709       <td><a href="#top-right-corner-box-def">top-right-corner</a></td>

  1710       <td>left</td>

  1711       <td>middle</td>

  1712       </tr>

  1713     <tr>

  1714       <td><a href="#left-top-box-def">left-top</a></td>

  1715       <td>center</td>

  1716       <td>top</td>

  1717       </tr>

  1718     <tr>

  1719       <td><a href="#left-middle-box-def">left-middle</a></td>

  1720       <td>center</td>

  1721       <td>middle</td>

  1722       </tr>

  1723     <tr>

  1724       <td><a href="#left-bottom-box-def">left-bottom</a></td>

  1725       <td>center</td>

  1726       <td>bottom</td>

  1727       </tr>

  1728     <tr>

  1729       <td><a href="#right-top-box-def">right-top</a></td>

  1730       <td>center</td>

  1731       <td>top</td>

  1732       </tr>

  1733     <tr>

  1734       <td><a href="#right-middle-box-def">right-middle</a></td>

  1735       <td>center</td>

  1736       <td>middle</td>

  1737       </tr>

  1738     <tr>

  1739       <td><a href="#right-bottom-box-def">right-bottom</a></td>

  1740       <td>center</td>

  1741       <td>bottom</td>

  1742       </tr>

  1743     <tr>

  1744       <td><a href="#bottom-left-corner-box-def">bottom-left-corner</a></td>

  1745       <td>right</td>

  1746       <td>middle</td>

  1747       </tr>

  1748     <tr>

  1749       <td><a href="#bottom-left-box-def">bottom-left</a></td>

  1750       <td>left</td>

  1751       <td>middle</td>

  1752       </tr>

  1753     <tr>

  1754       <td><a href="#bottom-center-box-def">bottom-center</a></td>

  1755       <td>center</td>

  1756       <td>middle</td>

  1757       </tr>

  1758     <tr>

  1759       <td><a href="#bottom-right-box-def">bottom-right</a></td>

  1760       <td>right</td>

  1761       <td>middle</td>

  1762       </tr>

  1763     <tr>

  1764       <td><a href="#bottom-right-corner-box-def">bottom-right-corner</a></td>

  1765       <td>left</td>

  1766       <td>middle</td>

  1767     </tr>

  1768   </tbody>

  1769 </table>

  1771 <div class="example">

  1773 <p>This example style sheet could be used to create a centered header with the

  1774 current chapter name:</p>

  1775 <pre>body {counter-reset: chapter;}

  1776 div.chapter {counter-increment: chapter;}

  1777 @page {

  1778 margin: 10%;

  1779 @top-center { content: "Chapter" counter(chapter) }

  1780 }

  1781 </pre>

  1782 </div>

  1784 <h2 id="page-size">Page Size</h2>

  1786 <p>People around the world use many different paper sizes. It is a goal of this

  1787 specification that web content should be adaptable to a range of different

  1788 sizes without having to write a specific style sheet for each paper size.</p>

  1790 <p>However, in some situations it is important that a certain page size achieves a

  1791 certain style. One way to achieve this goal is to utilize the 'size' property,

  1792 which indicates that the document should preferentially be displayed on a

  1793 surface of a certain size; another method is to use Media Queries [[MEDIAQ]]

  1794 which allow different style sheets to be applied to different page sizes.</p>

  1796 <h3 id="page-size-prop">Page size: the 'size' property</h3>

  1798 <table class="propdef" summary="definition of the size property">

  1799   <tr>

  1800     <th>Name:

  1801     <td><dfn id="size">size</dfn>

  1802   <tr>

  1803     <th>Value:

  1804     <td>&lt;length&gt;{1,2} | auto | [ &lt;page-size&gt; || [ portrait | landscape] ]

  1805   <tr>

  1806     <th>Initial:

  1807     <td>auto

  1808   <tr>

  1809     <td><em>Applies to:</em>

  1810     <td>page context

  1811   <tr>

  1812     <th>Inherited:

  1813     <td>N/A

  1814   <tr>

  1815     <th>Percentages:

  1816     <td>N/A

  1817   <tr>

  1818     <th>Media:

  1819     <td>paged

  1820   <tr>

  1821     <td><em>Computed value:</em>

  1822     <td>specified value

  1823 </table>

  1825 <p>This property specifies the target size and orientation of the

  1826 <a href="#page-box">page box</a>’s containing block.

  1827 In the general case, where one page box is rendered onto one <a href="#page-sheet">page sheet</a>,

  1828 the 'size' property also indicates the size of the destination page sheet.

  1830 <p>The size of a page box can either be "absolute" (fixed size) or "scalable"

  1831 (i.e., fitting available sheet sizes).

  1832 The first three values in the table below can be used to create scalable page

  1833 boxes.

  1834 Other values define a fixed-size page box, and thereby indicate the preferred

  1835 output media size. When possible, output should be rendered on the media size

  1836 indicated.

  1837 If the specified size is not available, the rules for

  1838 <a href="#renderingpages">transposing a page box to a different size</a>

  1839 apply.</p>

  1841 <p>If a <code>size</code> property declaration is qualified by a ''width'',

  1842 ''height'', ''device-width'', ''device-height'', ''aspect-ratio'',

  1843 ''device-aspect-ratio'' or ''orientation''

  1844 media query [[!MEDIAQ]] (or other conditional on the size of the paper), then

  1845 the declaration must be

  1846 <a href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignored</a>. Media

  1847 queries do not honor 'size': they assume the paper size that would be chosen

  1848 if no @page rules were specified.</p>

  1850 <div class=issue>

  1851   <p>It would be useful if media queries could respond at least

  1852   to sizes specified on an unqualified @page.

  1854   <p>Another option could be to do like ''@viewport'' rules

  1855   [[CSS-DEVICE-ADAPT]]:

  1856   First apply ''@page'' rules (matching which selectors?),

  1857   using the UA’s default page size for Media Queries and

  1858   <a href="http://www.w3.org/TR/css3-values/#viewport-relative-lengths">viewport-percentage lengths</a>

  1859   [[CSS3VAL]].

  1860   The resulting page size is the "base page size".

  1861   The entire set of stylesheets is applied again,

  1862   this time using the "base page size" for Media Queries

  1863   and viewport-percentage lengths.

  1864 </div>

  1867 <div class="example">

  1868   <p>In the following example

  1869   <pre>

  1870   @page {

  1871     size: 4in 6in;

  1872   }

  1874   @media (max-width: 6in) {

  1875     @page {

  1876       size: letter;

  1877     }

  1878   }

  1879   </pre>

  1880   <p>The second <code>size</code> declaration is ignored, i.e. the specified value

  1881   of the <code>size</code> property is <code>4in 6in</code>.

  1882 </div>

  1884 <table class="page-sizes">

  1885 <tr>

  1886 <th>Value</th>

  1887 <th>Description</th>

  1888 </tr>

  1889 <tr>

  1890 <td>auto</td>

  1891 <td>The page box will be set to a size and orientation chosen by the UA. In the

  1892 usual case, the page box size and orientation is chosen to match the target

  1893 media sheet.</td>

  1894 </tr>

  1895 <tr>

  1896 <td>landscape</td>

  1897 <td>Specifies that the page's content be printed in landscape orientation. The

  1898 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

  1899 is chosen by the UA.</td>

  1900 </tr>

  1901 <tr>

  1902 <td>portrait</td>

  1903 <td>Specifies that the page's content be printed in portrait orientation. The

  1904 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

  1905 is chosen by the UA.</td>

  1906 </tr>

  1907 <tr>

  1908 <td>&lt;length&gt;</td>

  1909 <td>The page box will be set to the given absolute dimension(s). If only one length

  1910 value is specified, it sets both the width and height of the page box (i.e.,

  1911 the box is a square). If two length values are specified, the first establishes

  1912 the page box width, and the second the page box height. Values in units of

  1913 <span class="css">'em'</span> and <span class="css">'ex'</span> refer to the

  1914 page context's font. Negative lengths are illegal.</td>

  1915 </tr>

  1916 <tr>

  1917 <td>&lt;page-size&gt;</td>

  1918 <td>A page size can be specified using one of the following media names. This is

  1919 the equivalent of specifying the <span class="css">'&lt;page-size&gt;'</span>

  1920 using length values. The definition of the the media names comes from

  1921 <cite>Media Standardized Names</cite> [[!PWGMSN]].

  1923 <dl>

  1925 <dt>A5</dt>

  1926 <dd>Equivalent to the size of ISO A5 media: 148mm wide and 210 mm high.</dd>

  1928 <dt>A4</dt>

  1929 <dd>Equivalent to the size of ISO A4 media: 210 mm wide and 297 mm high.</dd>

  1931 <dt>A3</dt>

  1932 <dd>Equivalent to the size of ISO A3 media: 297mm wide and 420mm high.</dd>

  1934 <dt>B5</dt>

  1935 <dd>Equivalent to the size of ISO B5 media: 176mm wide by 250mm high.</dd>

  1937 <dt>B4</dt>

  1938 <dd>Equivalent to the size of ISO B4 media: 250mm wide by 353mm high.</dd>

  1940 <dt>letter</dt>

  1941 <dd>Equivalent to the size of North American letter media: 8.5 inches wide and 11

  1942 inches high</dd>

  1944 <dt>legal</dt>

  1945 <dd>Equivalent to the size of North American legal: 8.5 inches wide by 14 inches

  1946 high.</dd>

  1948 <dt>ledger</dt>

  1949 <dd>Equivalent to the size of North American ledger: 11 inches wide by 17 inches

  1950 high.</dd>

  1951 </dl></td>

  1952 </tr>

  1953 </table>

  1955 <p>The '&lt;page-size&gt;' names can be used in conjunction with 'landscape' or

  1956 'portrait' to indicate both size and orientation.</p>

  1958 <h4>Some examples:</h4>

  1960 <div class="example">

  1961 <pre>

  1962 @page {

  1963 size: A4 landscape;

  1964 }

  1965 </pre>

  1967 <p>The above example sets the width of the page box to be 297mm and the height to

  1968 be 210mm. The page box in this example should be rendered on a page sheet size

  1969 of 210 mm by 297 mm.</p>

  1970 </div>

  1972 <div class="example">

  1974 <p>In the following example, the outer edges of the page box will align with the

  1975 page. The percentage value on the <span class="property">'margin'</span>

  1976 property is relative to the page size so if the page sheet dimensions are 210mm

  1977 x 297mm (i.e., A4), the margins are 21mm and 29.7mm. Assuming there are no page

  1978 borders or padding set in the UA default style sheet, the resulting page area

  1979 is 189mm by 367.3mm (210mm-21mm by 297mm-29.7mm).</p>

  1980 <pre>

  1981 @page {

  1982 size: auto;/* auto is the initial value */

  1983 margin: 10%;

  1984 }

  1985 </pre>

  1986 </div>

  1988 <div class="example">

  1989 <pre>

  1990 @page {

  1991 size: 8.5in 11in;/* width height */

  1992 }

  1993 </pre>

  1995 <p>The above example sets the width of the page box to be 8.5 inches and the

  1996 height to be 11 inches. This indicates that the page sheet size should be

  1997 8.5"x11" and the orientation 'portrait'.</p>

  1998 </div>

  2000 <h4 id="page-size-media-query">Media Queries</h4>

  2002 <p>This section is informative.</p>

  2004 <p>By using Media Queries [[MEDIAQ]], one style sheet can express different

  2005 stylistic preferences for different page sizes. Consider this example:</p>

  2007 <div class="example" style="font-size: 10pt;">

  2008 <pre>

  2009  /* style sheet for "A4" printing */

  2010  @media print and (width: 21cm) and (height: 29.7cm) {

  2011     @page {

  2012        margin: 3cm;

  2013     }

  2014  }

  2016  /* style sheet for "letter" printing */

  2017  @media print and (width: 8.5in) and (height: 11in) {

  2018     @page {

  2019         margin: 1in;

  2020     }

  2021  }

  2022 </pre>

  2023 </div>

  2025 <p>In the example above, "A4" sheets are given a "3cm" page margin, and "letter"

  2026 sheets are given a "1in" page margin.</p>

  2028 <h3 id="renderingpages">Rendering page boxes that do not fit a page sheet</h3>

  2030 <p>If a page box does not match the target page sheet dimensions, the user agent

  2031 should do one of the following (in order of preference):</p>

  2033 <ol>

  2034   <li>Render the page box at the indicated size on a larger page sheet.</li>

  2035   <li>Rotate the page box 90° if this will make the page box fit the page sheet.</li>

  2036   <li>Scale the page box to fit the page sheet. (The aspect ratio of the page box

  2037   <em class="RFC2119">should</em> be preserved.)</li>

  2038   <li>Graphically "slice" the page box onto multiple page sheets.</li>

  2039   <li>Clip overflowed content (least preferred).</li>

  2040 </ol>

  2042 <p>The user agent <em class="RFC2119">MAY</em> wish to consult the user before

  2043 performing these operations.</p>

  2045 <h3 id="positioning-page-box">Positioning the page box on the sheet</h3>

  2047 <p>When the page box is smaller than the page sheet, the user agent <em class="RFC2119">SHOULD</em> either:</p>

  2049 <ul>

  2050   <li>center the page box on the sheet since this will align double-sided pages

  2051   and avoid accidental loss of information that is printed near the edge of the

  2052   sheet; or</li>

  2053   <li>position the page box in the upper left corner of the page sheet

  2054   (or another corner,

  2055   based on the 'direction' and 'writing-mode' properties of the page box)

  2056   as this may minimize media consumption.</li>

  2057 </ul>

  2059 <p>The user agent <em class="RFC2119">MAY</em> wish to consult the user in this

  2060 regard.</p><!-- "Page selector and page context" -->

  2062 <h2 id="page-breaks">

  2063     <a id="pg-br-before-after"></a>

  2064     <a id="page-break-before"></a>

  2065     <a id="page-break-after"></a>

  2066     <a id="page-break-inside"></a>

  2067     <a id="breaks-inside"></a>

  2068     <a id="orphans"></a>

  2069     <a id="widows"></a>

  2070     <a id="allowed-pg-brk"></a>

  2071     <a id="brk-btw-blocks"></a>

  2072     <a id="brk-btw-lines"></a>

  2073     <a id="brk-end-block"></a>

  2074     <a id="forced-pg-brk"></a>

  2075     <a id="best-pg-brk"></a>

  2076     Page Breaks

  2077 </h2>

  2079 <p>

  2080   The CSS Fragmentation Module [[!CSS3-BREAK]] module

  2081   defines how and where CSS boxes

  2082   can be <i>fragmented</i>, including across page breaks.

  2083   It defines a few properties that indicate where the user agent

  2084   <em class="RFC2119">MAY</em> or <em class="RFC2119">MUST</em> break pages,

  2085   and on what page (left or right) the subsequent content resumes.

  2086   Each page break ends layout in the current <a href="#page-box">page box</a>

  2087   and causes remaining pieces of the document tree to be laid out

  2088   in a new page box.

  2089 </p>

  2091 <h3 id="using-named-pages">Using named pages: 'page'</h3>

  2092 <table class="propdef" summary="property definition">

  2093   <tr>

  2094     <th>Name:

  2095     <td><dfn id="page">page</dfn>

  2096   <tr>

  2097     <th>Value:

  2098     <td>auto | &lt;identifier&gt;

  2099   <tr>

  2100     <th>Initial:

  2101     <td>auto

  2102   <tr>

  2103     <th>Applies to:

  2104     <td>boxes that create <a href="http://www.w3.org/TR/css3-break/#btw-blocks">class A</a> break points

  2105   <tr>

  2106     <th>Inherited:

  2107     <td>no (but see prose)

  2108   <tr>

  2109     <th>Percentages:

  2110     <td>N/A

  2111   <tr>

  2112     <th>Media:

  2113     <td>paged

  2114   <tr>

  2115     <th>Computed value:

  2116     <td>specified value

  2117 </table>

  2119 <p>

  2120   The 'page' property is used to specify a particular type of page (called a <dfn>named page</dfn>)

  2121   on which an element <em class="RFC2119">MUST</em> be displayed.

  2122   If necessary, a <i>forced page break</i> is introduced

  2123   and a new page generated of the specified type.

  2125 <p class="note">

  2126   This page can be styled by using the same type name

  2127   in a <a href="#page-selectors">page selector</a>.

  2129 <p>

  2130   Page type names are case-sensitive identifiers.

  2131   However the ''auto'' value, being a CSS keyword, is

  2132   <a href="http://www.w3.org/TR/CSS21/syndata.html#characters">ASCII case-insensitive</a>.

  2134 <p>

  2135   The 'page' property does not inherit.

  2136   However, if the 'page' value on an element is ''auto'',

  2137   then its used value is the value specified

  2138   on its nearest ancestor with a non-auto value.

  2139   When specified on the root element,

  2140   the used value for ''auto'' is the empty string.

  2142   <!-- See http://www.w3.org/TR/2007/WD-css3-gcpm-20070504/#named3 -->

  2144 <p>

  2145   Because a previous version of this specification

  2146   indicated that the 'page' property is inherited,

  2147   an implementation that inherits the 'page' property

  2148   and treats ''auto'' as always naming the empty string

  2149   remains conformant to CSS Paged Media Level 3.

  2150   Note that this exception will be removed in Level 4.

  2151   Therefore authors should not explicitly specify the ''auto'' value

  2152   on a descendant of an element with a non-''auto'' value,

  2153   as the resulting behavior will be unpredictable.

  2155 <p>

  2156   The 'page' property works as follows:

  2158 <ol>

  2160   <li>

  2161     First, any ''auto'' values are resolved against non-''auto'' ancestors

  2162     (as specified above).

  2164   <li>

  2165     Next,

  2166     a <dfn>start 'page' value</dfn> and <dfn>end 'page' value</dfn>

  2167     is determined for each box

  2168     as the value (if any) propagated from

  2169     its first or last child box (respectively),

  2170     else the used value on the box itself.

  2171     A child propagates its own

  2172     <i title="start page value">start</i> or <i>end 'page' value</i>

  2173     if and only if the 'page' property applies to it.

  2175     <p class="note">

  2176       Note:

  2177       A first or last child <em>box</em> is not always generated by

  2178       a first or last child <em>element</em>.

  2179       For example,

  2180       an element could only have a previous sibling with 'display: none'

  2181       which does not generate any box.

  2183   <li>

  2184     The first printed page’s type is the <i>start 'page' value</i> of the root.

  2186   <li>

  2187     If for any two boxes meeting at a <a href="http://www.w3.org/TR/css3-break/#btw-blocks">class A</a> break point,

  2188     the <i>end 'page' value</i> of the box preceding the break

  2189     and <i>start 'page' value</i> of the box succeeding the break

  2190     do not match,

  2191     then a page break is forced between the two boxes,

  2192     and content after the break resumes on a page box of the named type.

  2193 </ol>

  2195 <p class="note">

  2196   Essentially, the two 'page' values compared are those from the deepest boxes

  2197   meeting at the <a href="http://www.w3.org/TR/css3-break/#btw-blocks">class A break point</a>,

  2198   ignoring any subtrees rooted by boxes to which the 'page' property does not apply.

  2200 <p>See [[!CSS3-BREAK]] for additional details on page breaks.

  2202 <div class="example">

  2204 <p>In this example, the two tables are rendered on landscape pages (indeed, on the

  2205 same page, if they fit). The page type "narrow" is used for the &lt;p&gt; after

  2206 the second table, as the page properties for the table element are no longer in

  2207 effect:</p>

  2208 <pre>

  2209 @page narrow { size: 9cm 18cm }

  2210 @page rotated { size: landscape }

  2211 div { page: narrow }

  2212 table { page: rotated }

  2213 </pre>with this document:

  2214 <pre>

  2215 &lt;div&gt;

  2216 &lt;table&gt;...&lt;/table&gt;

  2217 &lt;table&gt;...&lt;/table&gt;

  2218 &lt;p&gt;This text is rendered on a 'narrow' page&lt;/p&gt;

  2219 &lt;/div&gt;

  2220 </pre>

  2221 </div>

  2223 <div class="example">

  2224   <p>In Japanese documents, sometimes different parts of a single document

  2225   will have different <i lang="ja-Latn">kihon hanmen</i>. [[JLREQ]]

  2226   The 'page' property, together with ''@page'' rules specifying different page widths,

  2227   can accomodate this type of layout:

  2228   <pre>

  2229 &lt;!DOCTYPE html>

  2230 &lt;html lang="ja">

  2231   &lt;style>

  2232     html   { writing-mode: vertical-rl;

  2233              line-height: 1.6; }

  2234     .main  { page: main;

  2235              columns: 2; column-gap: 1rem; }

  2236     .index { page: index;

  2237              columns: 3; column-gap: 1rem; }

  2238     @page       { margin: auto;    /* center kihon hanmen on page */

  2239                   width:  40rem; } /* 1.6 &times; 25 lines        */

  2240     @page main  { height: 61rem; } /* 2 &times; 30 chars + 1 &times; gap */

  2241     @page index { height: 62rem; } /* 3 &times; 20 chars + 2 &times; gap */

  2242   &lt;/style>

  2243   &lt;section class="main"> ... &lt;/section>

  2244   &lt;section class="index"> ... &lt;/section>

  2245 &lt;/html>

  2246 </pre>

  2247 </div>

  2250 <h2 id="image-properties">Image Properties</h2>

  2252 <p class="note">This section has been moved to [[CSS3-IMAGES]].</p>

  2254 <h2 class="no-num" id="properties-list">Appendix A: Applicable CSS2.1 Properties</h2>

  2256 <h3 class="no-num" id="page-property-list">

  2257   CSS 2.1 Properties that apply within the page context</h3>

  2259 <p>

  2260   This list is described in the

  2261   <a href="#page-properties">Page Properties</a> section.

  2263 <table class="property-list">

  2264   <tbody>

  2265     <tr><td rowspan="2"><a href="http://www.w3.org/TR/CSS21/visuren.html#direction">bidi properties</a>

  2266         <td>direction

  2267   <tbody>

  2268     <tr><td rowspan="6"><a href="http://www.w3.org/TR/CSS21/colors.html#background-properties">background properties</a>

  2269         <td>background-color

  2270     <tr><td>background-image

  2271     <tr><td>background-repeat

  2272     <tr><td>background-attachment

  2273     <tr><td>background-position

  2274     <tr><td>background

  2275   <tbody>

  2276     <tr><td rowspan="20"><a href="http://www.w3.org/TR/CSS21/box.html#border-properties">border properties</a>

  2277         <td>border-top-width

  2278     <tr><td>border-right-width

  2279     <tr><td>border-bottom-width

  2280     <tr><td>border-left-width

  2281     <tr><td>border-width

  2282     <tr><td>border-top-color

  2283     <tr><td>border-right-color

  2284     <tr><td>border-bottom-color

  2285     <tr><td>border-left-color

  2286     <tr><td>border-color

  2287     <tr><td>border-top-style

  2288     <tr><td>border-right-style

  2289     <tr><td>border-bottom-style

  2290     <tr><td>border-left-style

  2291     <tr><td>border-short-style

  2292     <tr><td>border-top

  2293     <tr><td>border-right

  2294     <tr><td>border-bottom

  2295     <tr><td>border-left

  2296     <tr><td>border

  2297   <tbody>

  2298     <tr><td rowspan="2"><a href="http://www.w3.org/TR/CSS21/generate.html#counters">counter properties</a>

  2299         <td>counter-reset

  2300     <tr><td>counter-increment

  2301   <tbody>

  2302     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/colors.html#propdef-color">color</a>

  2303   <tbody>

  2304     <tr><td rowspan="6"><a href="http://www.w3.org/TR/CSS21/fonts.html">font properties</a>

  2305         <td>font-family

  2306     <tr><td>font-size

  2307     <tr><td>font-style

  2308     <tr><td>font-variant

  2309     <tr><td>font-weight

  2310     <tr><td>font

  2311   <tbody>

  2312     <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>

  2313         <td>height

  2314     <tr><td>min-height

  2315     <tr><td>max-height

  2316   <tbody>

  2317     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/visudet.html#line-height">line-height</a>

  2318   <tbody>

  2319     <tr><td rowspan="5"><a href="http://www.w3.org/TR/CSS21/box.html#margin-properties">margin properties</a>

  2320         <td>margin-top

  2321     <tr><td>margin-right

  2322     <tr><td>margin-bottom

  2323     <tr><td>margin-left

  2324     <tr><td>margin

  2325   <tbody>

  2326     <tr><td rowspan="5"><a href="http://www.w3.org/TR/CSS21/ui.html#dynamic-outlines">outline properties</a>

  2327         <td>outline-width

  2328     <tr><td>outline-style

  2329     <tr><td>outline-color

  2330     <tr><td>outline

  2331   <tbody>

  2332     <tr><td rowspan="5"><a href="http://www.w3.org/TR/CSS21/box.html#padding-properties">padding properties</a>

  2333         <td>padding-top

  2334     <tr><td>padding-right

  2335     <tr><td>padding-bottom

  2336     <tr><td>padding-left

  2337     <tr><td>padding

  2338   <tbody>

  2339     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/generate.html#quotes-specify">quotes</a>

  2340   <tbody>

  2341     <tr><td rowspan="7"><a href="http://www.w3.org/TR/CSS21/text.html">text properties</a>

  2342         <td>letter-spacing

  2343     <tr><td>text-align

  2344     <tr><td>text-decoration

  2345     <tr><td>text-indent

  2346     <tr><td>text-transform

  2347     <tr><td>white-space

  2348     <tr><td>word-spacing

  2349   <tbody>

  2350     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/visufx.html#visibility">visibility</a>

  2351   <tbody>

  2352     <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>

  2353         <td>width

  2354     <tr><td>min-width

  2355     <tr><td>max-width

  2356 </table>

  2359 <h3 class="no-num" id="margin-property-list">

  2360   CSS 2.1 properties that apply within the margin contexts</h3>

  2362 <p>

  2363   This list is described in the

  2364   <a href="#page-properties">Page Properties</a> section.

  2366 <table class="property-list">

  2367   <tbody>

  2368     <tr><td rowspan="2"><a href="http://www.w3.org/TR/CSS21/visuren.html#direction">bidi properties</a>

  2369         <td>direction

  2370     <tr><td>unicode-bidi

  2371   <tbody>

  2372     <tr><td rowspan="6"><a href="http://www.w3.org/TR/CSS21/colors.html#background-properties">background properties</a>

  2373         <td>background-color

  2374     <tr><td>background-image

  2375     <tr><td>background-repeat

  2376     <tr><td>background-attachment

  2377     <tr><td>background-position

  2378     <tr><td>background

  2379   <tbody>

  2380     <tr><td rowspan="20"><a href="http://www.w3.org/TR/CSS21/box.html#border-properties">border properties</a>

  2381         <td>border-top-width

  2382     <tr><td>border-right-width

  2383     <tr><td>border-bottom-width

  2384     <tr><td>border-left-width

  2385     <tr><td>border-width

  2386     <tr><td>border-top-color

  2387     <tr><td>border-right-color

  2388     <tr><td>border-bottom-color

  2389     <tr><td>border-left-color

  2390     <tr><td>border-color

  2391     <tr><td>border-top-style

  2392     <tr><td>border-right-style

  2393     <tr><td>border-bottom-style

  2394     <tr><td>border-left-style

  2395     <tr><td>border-short-style

  2396     <tr><td>border-top

  2397     <tr><td>border-right

  2398     <tr><td>border-bottom

  2399     <tr><td>border-left

  2400     <tr><td>border

  2401   <tbody>

  2402     <tr><td rowspan="2"><a href="http://www.w3.org/TR/CSS21/generate.html#counters">counter properties</a>

  2403         <td>counter-reset

  2404     <tr><td>counter-increment

  2405   <tbody>

  2406     <tr><td colspan="2"><a href="">content</a>

  2407   <tbody>

  2408     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/colors.html#propdef-color">color</a>

  2409   <tbody>

  2410     <tr><td rowspan="6"><a href="http://www.w3.org/TR/CSS21/fonts.html">font properties</a>

  2411         <td>font-family

  2412     <tr><td>font-size

  2413     <tr><td>font-style

  2414     <tr><td>font-variant

  2415     <tr><td>font-weight

  2416     <tr><td>font

  2417   <tbody>

  2418     <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>

  2419         <td>height

  2420     <tr><td>min-height

  2421     <tr><td>max-height

  2422   <tbody>

  2423     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/visudet.html#line-height">line-height</a>

  2424   <tbody>

  2425     <tr><td rowspan="5"><a href="http://www.w3.org/TR/CSS21/box.html#margin-properties">margin properties</a>

  2426         <td>margin-top

  2427     <tr><td>margin-right

  2428     <tr><td>margin-bottom

  2429     <tr><td>margin-left

  2430     <tr><td>margin

  2431   <tbody>

  2432     <tr><td rowspan="5"><a href="http://www.w3.org/TR/CSS21/ui.html#dynamic-outlines">outline properties</a>

  2433         <td>outline-width

  2434     <tr><td>outline-style

  2435     <tr><td>outline-color

  2436     <tr><td>outline

  2437   <tbody>

  2438     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/visufx.html#overflow">overflow</a>

  2439   <tbody>

  2440     <tr><td rowspan="5"><a href="http://www.w3.org/TR/CSS21/box.html#padding-properties">padding properties</a>

  2441         <td>padding-top

  2442     <tr><td>padding-right

  2443     <tr><td>padding-bottom

  2444     <tr><td>padding-left

  2445     <tr><td>padding

  2446   <tbody>

  2447     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/generate.html#quotes-specify">quotes</a>

  2448   <tbody>

  2449     <tr><td rowspan="7"><a href="http://www.w3.org/TR/CSS21/text.html">text properties</a>

  2450         <td>letter-spacing

  2451     <tr><td>text-align

  2452     <tr><td>text-decoration

  2453     <tr><td>text-indent

  2454     <tr><td>text-transform

  2455     <tr><td>white-space

  2456     <tr><td>word-spacing

  2457   <tbody>

  2458     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/visudet.html#line-height">vertical-align</a>

  2459   <tbody>

  2460     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/visufx.html#visibility">visibility</a>

  2461   <tbody>

  2462     <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>

  2463         <td>width

  2464     <tr><td>min-width

  2465     <tr><td>max-width

  2466   <tbody>

  2467     <tr><td colspan="2"><a href="http://www.w3.org/TR/CSS21/visuren.html#z-index">z-index</a>

  2468 </table>

  2470 <h2 class="no-num" id="transfer-possibilities">Appendix B: Transfer Possibilities</h2>

  2472 <p>Often, but not always, the page box has a one-to-one correspondence to the

  2473 physical surface onto which the document is ultimately rendered. The CSS3 page

  2474 model specifies formatting within the page box, but it is the user agent's

  2475 responsibility to transfer the page box to the sheet. Some user agent transfer

  2476 possibilities that are not addressed by CSS3 include:</p>

  2478 <ul id="complex-usecases">

  2479   <li>Transferring one page box to one sheet (e.g. single-sided printing);</li>

  2480   <li>Transferring two page boxes to the front and back surfaces of the same

  2481   sheet (e.g. double-sided printing);</li>

  2482   <li>Transferring N (small) page boxes to one sheet (called "N-up");</li>

  2483   <li>Transferring one (large) page box to N x M sheets (called "tiling");</li>

  2484   <li>Creating signatures. A <dfn>signature</dfn> is a group of pages printed on

  2485   a sheet, which, when folded and trimmed like a book, appear in their proper

  2486   sequence;</li>

  2487   <li>Printing one document to multiple output trays;</li>

  2488   <li>Generating files containing print instructions.</li>

  2489 </ul>

  2491 <h2 class="no-num" id="changes">Changes</h2>

  2493 <p>

  2494   Changes since the <a href="http://www.w3.org/TR/2006/WD-css3-page-20061010/">10 October 2006 Working Draft</a> are:

  2495 </p>

  2497 <ul>

  2498   <li>The first printed page can be <a href="#using-named-pages">named</a>.

  2500   <li>The '':blank'' pseudo-class was imported

  2501     from the <a href="http://dev.w3.org/csswg/css3-gcpm/">Generated Content for Paged Media</a> module.

  2503   <li>''@page'' rules can now take multiple comma separated selectors,

  2504     each selector can have multiple pseudo-classes.

  2506     <div class="example">

  2507       <pre>@page :first, :blank { @bottom-center { content: none } }</pre>

  2508       <pre>@page :first:left { @bottom-left { content: none } }</pre>

  2509     </div>

  2511   <li>Margin boxes are renamed <a href="#margin-boxes">page-margin boxes</a>,

  2512     to avoid confusion with the margin area of each box.

  2514   <li>The <a href="#variable-sizing">Variable Dimension</a>

  2515     layout rules for page-margin boxes have been much simplified

  2516     to not require quadratic optimization.

  2518   <li>The relative <a href="#painting">painting order</a>

  2519     of page-margin boxes and page content has changed.

  2521   <li>The description of page breaks and definition of related properties

  2522     (except for the 'page' property)

  2523     have been moved to the CSS Fragmentation Module. [[!CSS3-BREAK]]

  2525   <li>The 'fit' and 'fit-position' properties

  2526     are renamed to 'object-fit' and 'object-position',

  2527     redefined to enable additional use cases,

  2528     and moved to the CSS3 Image Values and Replaced Content module.

  2529     [[CSS3-IMAGES]]

  2531   <li>The default stacking order of page-magin boxes is now defined.

  2533   <li>Support for the 'z-index' property on page-margin boxes

  2534     is not optional anymore.

  2536   <li>Each page-margin box eastablishes a stacking context.

  2538   <li>Many miscellaneous clarifications

  2539     and editorial improvements have been incorporated.

  2541 </ul>

  2544 <h2 class="no-num" id="references">References</h2>

  2546 <h3 class="no-num" id="normative-references">Normative References</h3><!--normative-->

  2548 <h3 class="no-num" id="informative-references">Informative References</h3><!--informative-->

  2549 </div>

  2550 </div>

  2551 </body>

  2552 </html>

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