css3-transitions/Overview.src.html

Thu, 12 Jul 2012 17:35:04 -0700

author
L. David Baron <dbaron@dbaron.org>
date
Thu, 12 Jul 2012 17:35:04 -0700
changeset 6223
8f1870702065
parent 6218
13621f209435
child 6224
81d3d19891b6
permissions
-rw-r--r--

Actually describe how the interpolation works.

     1 <!DOCTYPE html PUBLIC '-//W3C//DTD HTML 4.01//EN'
     2   'http://www.w3.org/TR/html4/strict.dtd'>
     4 <html lang="en">
     5 <head>
     6   <title>CSS Transitions</title>
     7   <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
     8   <link rel="stylesheet" type="text/css" href="../default.css">
     9   <style type="text/css">
    10     table.animatable-properties {
    11       border-collapse: collapse;
    12     }
    13     table.animatable-properties td {
    14       padding: 0.2em 1em;
    15       border: 1px solid black;
    16     }
    17   </style>
    18   <link rel="stylesheet" type="text/css" href="http://www.w3.org/StyleSheets/TR/W3C-ED.css">
    19 </head>
    21 <body>
    23 <div class="head">
    24 <!--logo-->
    26 <h1>CSS Transitions</h1>
    28 <h2 class="no-num no-toc">[LONGSTATUS] [DATE]</h2>
    29 <dl>
    30   <dt>This version:
    31     <dd>
    32     <a href="[VERSION]">
    33       http://dev.w3.org/csswg/css3-transitions/</a>
    34       <!--http://www.w3.org/TR/[YEAR]/WD-[SHORTNAME]-[CDATE]/-->
    35   <dt>Latest version:
    36     <dd><a href="http://www.w3.org/TR/css3-transitions/">
    37       [LATEST]</a>
    38   <dt>Editor's draft:
    39     <dd><a href="http://dev.w3.org/csswg/[SHORTNAME]/">http://dev.w3.org/csswg/[SHORTNAME]/</a>
    40   <dt>Previous version:
    41     <dd><a href="http://www.w3.org/TR/2012/WD-css3-transitions-20120403/">
    42       http://www.w3.org/TR/2012/WD-css3-transitions-20120403/</a>
    43   <dt id="editors-list">Editors:
    44     <dd><a href="mailto:dino@apple.com">Dean Jackson</a> (<a
    45       href="http://www.apple.com/">Apple Inc</a>)
    46     <dd><a href="mailto:hyatt@apple.com">David Hyatt</a> (<a
    47       href="http://www.apple.com/">Apple Inc</a>)
    48     <dd><a href="mailto:cmarrin@apple.com">Chris Marrin</a> (<a
    49       href="http://www.apple.com/">Apple Inc</a>)
    50     <dd class=vcard><a class=fn href="http://dbaron.org/">L. David Baron</a> (<a
    51       class=org href="http://www.mozilla.org/">Mozilla</a>)
    53   <dt>Issues list:
    54     <dd><a href="https://www.w3.org/Bugs/Public/buglist.cgi?query_format=advanced&amp;product=CSS&amp;component=Transitions&amp;resolution=---&amp;cmdtype=doit">in Bugzilla</a>
    56   <dt>Discussion:</dt>
    57     <dd><a href="http://lists.w3.org/Archives/Public/www-style/">www-style@w3.org</a> with subject line &ldquo;<kbd>[[SHORTNAME]] <var>&hellip; message topic &hellip;</var></kbd>&rdquo;
    59   <dt>Test suite:
    60     <dd>none yet
    61 </dl>
    63 <!--copyright-->
    65 <hr title="Separator for header">
    66 </div>
    68 <h2 class="no-num no-toc" id="abstract">Abstract</h2>
    70 <p>CSS Transitions allows property changes in CSS values to occur smoothly
    71   over a specified duration.
    73 <h2 class="no-num no-toc" id="status">Status of this document</h2>
    74 <!--status-->
    76 <p>
    77   The <a href="ChangeLog">list of changes made to this specification</a> is
    78   available.
    79 </p>
    81 <h2 class="no-num no-toc" id="contents">Table of contents</h2>
    82 <!--toc-->
    85 <h2 id="introduction">Introduction</h2>
    87       <p><em>This section is not normative.</em>
    88       <p>
    89         This document introduces new CSS features to enable <em>implicit transitions</em>, which describe how CSS properties can be made to change smoothly from one value to another over a given duration.
    90       </p>
    92 <h2 id="transitions"><a id="transitions-">Transitions</a></h2>
    93       <p>
    94         Normally when the value of a CSS property changes, the rendered result is instantly updated, with the affected elements immediately changing from the old property value to the new property value. This section describes a way to specify transitions using new CSS properties. These properties are used to animate smoothly from the old state to the new state over time.
    95       </p>
    96       <p>
    97         For example, suppose that transitions of one second have been defined on the <code class="property">'left'</code> and
    98         <code class="property">'background-color'</code> properties. The following diagram illustrates the effect of updating those properties on an element, in this case moving it to the right and changing the background from red to blue. This assumes other transition parameters still have their default values.
    99       </p>
   100       <div class="figure">
   101         <img src="transition1.png" alt="">
   102       </div>
   103       <p class="caption">
   104         Transitions of <code class="property">'left'</code> and <code class="property">'background-color'</code>
   105       </p>
   106       <p>
   107         Transitions are a presentational effect. The computed value of a property transitions over time from the old value to the new value. Therefore if a script queries the computed style of a property as it is transitioning, it will see an intermediate value that represents the current animated value of the property.
   108       </p>
   109       <p>
   110         Only animatable CSS properties can be transitioned. See the table at the end of this document for a list 
   111         of properties that are animatable.
   112       </p>
   113       <p>
   114         The transition for a property is defined using a number of new properties. For example:
   115       </p>
   116       <div class="example">
   117         <p style="display:none">
   118           Example(s):
   119         </p>
   120         <pre>
   121   div {
   122     transition-property: opacity;
   123     transition-duration: 2s;
   124   }
   125   </pre>The above example defines a transition on the <code class="property">'opacity'</code> property that, when a new value is assigned to it, will cause a smooth change between the old value and the new value over a period of two seconds.
   126       </div>
   127       <p>
   128         Each of the transition properties accepts a comma-separated list, allowing multiple transitions to be defined, each acting on a different property. In this case, the individual transitions take their parameters from the same index in all the lists. For example:
   129       </p>
   130       <div class="example">
   131         <p style="display:none">
   132           Example(s):
   133         </p>
   134         <pre>
   135   div {
   136     transition-property: opacity, left;
   137     transition-duration: 2s, 4s;
   138   }
   140   </pre>This will cause the <code class="property">'opacity'</code> property to transition over a period of two seconds and the left property to transition over a period of four seconds.
   141       </div>
   143       <p id="list-matching">
   144         In the case where the lists of values in transition properties
   145         do not have the same length, the length of the
   146         'transition-property' list determines the number of items in
   147         each list examined when starting transitions.  The lists are
   148         matched up from the first value: excess values at the end are
   149         not used.  If one of the other properties doesn't have enough
   150         comma-separated values to match the number of values of
   151         'transition-property', the UA must calculate its used value by
   152         repeating the list of values until there are enough.  This
   153         truncation or repetition does not affect the computed value.
   154         <span class="note">
   155           Note: This is analogous to the behavior of the 'background-*'
   156           properties, with 'background-image' analogous to
   157           'transition-property'.
   158         </span>
   159       </p>
   161       <div class="example">
   162         <p style="display:none">
   163           Example(s):
   164         </p>
   165       <pre>
   166       div {
   167         transition-property: opacity, left, top, width;
   168         transition-duration: 2s, 1s;
   169       }
   170       </pre>The above example defines a transition on the <code class="property">'opacity'</code> property of 2 seconds duration, a
   171       transition on the <code class="property">'left'</code> property of 1
   172       second duration, a transition on the <code class="property">'top'</code> property of 2 seconds duration and a
   173       transition on the <code class="property">'width'</code> property of 1
   174       second duration.
   176       </div>
   178       <!-- ======================================================================================================= -->
   179       <h3 id=transition-property-property><a id=the-transition-property-property->
   180         The <code class="property">'transition-property'</code> Property
   181       </a></h3>
   182       <p>
   183         The <code class="property">'transition-property'</code> property specifies the name of the CSS property to which the transition is applied.
   184       </p>
   185       <div class="issue">
   186         We may ultimately want to support a keypath syntax for this property. A keypath syntax would enable different transitions to be specified for components of a property. For example the blur of a shadow could have a different transition than the color of a shadow.
   187       </div>
   188       <table class="propdef">
   189         <tbody>
   190           <tr>
   191             <td>
   192               <em>Name:</em>
   193             </td>
   194             <td>
   195               <dfn id="transition-property">transition-property</dfn>
   196             </td>
   197           </tr>
   198           <tr>
   199             <td>
   200               <em>Value:</em>
   201             </td>
   202             <td>
   203               none | [ all | &lt;IDENT&gt; ] [ ',' [ all | &lt;IDENT&gt; ] ]*
   204             </td>
   205           </tr>
   206           <tr>
   207             <td>
   208               <em>Initial:</em>
   209             </td>
   210             <td>
   211               all
   212             </td>
   213           </tr>
   214           <tr>
   215             <td>
   216               <em>Applies&nbsp;to:</em>
   217             </td>
   218             <td>
   219               all elements, :before and :after pseudo elements
   220             </td>
   221           </tr>
   222           <tr>
   223             <td>
   224               <em>Inherited:</em>
   225             </td>
   226             <td>
   227               no
   228             </td>
   229           </tr>
   230           <tr>
   231             <td>
   232               <em>Percentages:</em>
   233             </td>
   234             <td>
   235               N/A
   236             </td>
   237           </tr>
   238           <tr>
   239             <td>
   240               <em>Media:</em>
   241             </td>
   242             <td>
   243               visual
   244             </td>
   245           </tr>
   246           <tr>
   247             <td>
   248               <em>Computed value:</em>
   249             </td>
   250             <td>
   251               Same as specified value.
   252             </td>
   253           </tr>
   254         </tbody>
   255       </table>
   257       <p>
   258         A value of 'none' means that no property will transition.
   259         Otherwise, a list of properties to be transitioned, or the
   260         keyword 'all' which indicates that all properties are to be
   261         transitioned, is given.
   262       </p>
   264       <p>
   265         If one of the identifiers listed is not a recognized property
   266         name or is not an animatable property, the implementation must
   267         still start transitions on the animatable properties in the
   268         list using the duration, delay, and timing function at their
   269         respective indices in the lists for 'transition-duration',
   270         'transition-delay', and 'transition-timing-function'.  In other
   271         words, unrecognized or non-animatable properties must be kept in
   272         the list to preserve the matching of indices.
   273       </p>
   274       <p class="issue">
   275         Are 'none', 'inherit', and 'initial' allowed as items in
   276         a list of identifiers (of length greater than one)?
   277       </p>
   278       <p>
   279         For the keyword 'all', or if one of the identifiers listed is a
   280         shorthand property, implementations must start transitions for
   281         any of its longhand sub-properties that are animatable (or, for
   282         'all', all animatable properties), using the duration, delay,
   283         and timing function at the index corresponding to the shorthand.
   284       </p>
   285       <p>
   286         If a property is specified multiple times in the value of
   287         'transition-property' (either on its own, via a shorthand that
   288         contains it, or via the 'all' value), then the transition that
   289         starts uses the duration, delay, and timing function at the
   290         index corresponding to the <em>last</em> item in the value of
   291         'transition-property' that calls for animating that property.
   292       </p>
   293       <p class="note">
   294         Note:  The <code class="property">all</code> value and shorthand
   295         properties work in similar ways, so the <code
   296         class="property">all</code> value is just like a shorthand that
   297         covers all properties.
   298       </p>
   300       <!-- ======================================================================================================= -->
   301       <h3 id=transition-duration-property><a id=the-transition-duration-property->
   302         The <code class="property">'transition-duration'</code> Property
   303       </a></h3>
   304       <p>
   305         The <code class="property">'transition-duration'</code> property defines the length of time that a transition takes.
   306       </p>
   307       <table class="propdef">
   308         <tbody>
   309           <tr>
   310             <td>
   311               <em>Name:</em>
   312             </td>
   313             <td>
   314               <dfn id="transition-duration">transition-duration</dfn>
   315             </td>
   316           </tr>
   317           <tr>
   318             <td>
   319               <em>Value:</em>
   320             </td>
   321             <td>
   322               &lt;time&gt; [, &lt;time&gt;]*
   323             </td>
   324           </tr>
   325           <tr>
   326             <td>
   327               <em>Initial:</em>
   328             </td>
   329             <td>
   330               0s
   331             </td>
   332           </tr>
   333           <tr>
   334             <td>
   335               <em>Applies&nbsp;to:</em>
   336             </td>
   337             <td>
   338               all elements, :before and :after pseudo elements
   339             </td>
   340           </tr>
   341           <tr>
   342             <td>
   343               <em>Inherited:</em>
   344             </td>
   345             <td>
   346               no
   347             </td>
   348           </tr>
   349           <tr>
   350             <td>
   351               <em>Percentages:</em>
   352             </td>
   353             <td>
   354               N/A
   355             </td>
   356           </tr>
   357           <tr>
   358             <td>
   359               <em>Media:</em>
   360             </td>
   361             <td>
   362               interactive
   363             </td>
   364           </tr>
   365           <tr>
   366             <td>
   367               <em>Computed value:</em>
   368             </td>
   369             <td>
   370               Same as specified value.
   371             </td>
   372           </tr>
   373         </tbody>
   374       </table>
   375       <p>
   376         This property specifies how long the transition from the old value to the new value should take. By default the value is '0s', meaning that the transition is immediate (i.e. there will be no animation). A negative value for <code class="property">transition-duration</code> renders the declaration invalid.
   377       </p>
   379       <!-- =======================================================================================================   
   380         -->
   382       <h3 id=transition-timing-function-property><a id=transition-timing-function_tag>
   383         The <code class="property">'transition-timing-function'</code> Property
   384       </a></h3>
   385       <p>
   386         The <code class="property">'transition-timing-function'</code> property
   387         describes how the intermediate values used during a transition will be
   388         calculated. It allows for a transition to change speed over its
   389         duration. These effects are commonly called <em>easing</em> functions.
   390         In either case, a mathematical function that provides a smooth curve is
   391         used.
   392       </p>
   393       <p>
   394         Timing functions are either defined as a stepping function or 
   395         a <a
   396         href="http://en.wikipedia.org/wiki/B%C3%A9zier_curve#Cubic_B.C3.A9zier_curves">cubic
   397         B&eacute;zier curve</a>. 
   398         The timing function takes as its input
   399         the current elapsed percentage of the transition duration
   400         and outputs the percentage of the way the transition is
   401         from its start value to its end value.
   402         How this output is used is defined by
   403         the <a href="#animatable-types">interpolation rules</a>
   404         for the value type.
   405       </p>
   406       <p>
   407         A <a href="http://en.wikipedia.org/wiki/Step_function">stepping</a>
   408         function is defined by a number that divides the domain of operation
   409         into equally sized intervals. Each subsequent interval is a equal step
   410         closer to the goal state. The function also specifies whether the
   411         change in output percentage happens at the start or end of the
   412         interval (in other words, if 0% on the input percentage is the point
   413         of initial change).
   414       </p>
   415       <div class="figure">
   416         <img src="step.png" alt="The step timing function splits
   417           the function domain into a number of disjoint straight line
   418           segments. steps(1, start) is a function whose
   419           output value is 1 for all input values. steps(1, end) is a function whose
   420           output value is 0 for all input values less than 1, and output
   421           is 1 for the input value of 1. steps(3, start) is a function that
   422           divides the input domain into three segments, each 1/3 in length,
   423           and 1/3 above the previous segment, with the first segment starting
   424           at 1/3. steps(3, end) is a function that
   425           divides the input domain into three segments, each 1/3 in length,
   426           and 1/3 above the previous segment, with the first segment starting
   427           at 0.">
   428       </div>
   429       <p class="caption">
   430         Step timing functions
   431       </p>
   432       <p>
   433         A <a
   434         href="http://en.wikipedia.org/wiki/B%C3%A9zier_curve#Cubic_B.C3.A9zier_curves">cubic
   435         B&eacute;zier curve</a> is defined by four control points, P<sub>0</sub>
   436         through P<sub>3</sub> (see Figure 1). P<sub>0</sub> and P<sub>3</sub>
   437         are always set to (0,0) and (1,1). The <code class="property">'transition-timing-function'</code> property is used
   438         to specify the values for points P<sub>1</sub> and P<sub>2</sub>. These
   439         can be set to preset values using the keywords listed below, or can be
   440         set to specific values using the <code class="css">'cubic-bezier'</code> function.
   441         In the <code class="css">'cubic-bezier'</code> function, P<sub>1</sub> and
   442         P<sub>2</sub> are each specified by both an X and Y value.
   443       </p>
   444       <div class="figure">
   445         <img src="TimingFunction.png" alt="The B&eacute;zier timing function is a
   446           smooth curve from point P0 = (0,0) to point P3 = (1,1). The
   447           length and orientation of the line segment P0-P1 determines
   448           the tangent and the curvature of the curve at P0 and the
   449           line segment P2-P3 does the same at P3.">
   450       </div>
   451       <p class="caption">
   452         B&eacute;zier Timing Function Control Points
   453       </p>
   454       <table class="propdef">
   455         <tbody>
   456           <tr>
   457             <td>
   458               <em>Name:</em>
   459             </td>
   460             <td>
   461               <dfn id="transition-timing-function">transition-timing-function</dfn>
   462             </td>
   463           </tr>
   464           <tr>
   465             <td>
   466               <em>Value:</em>
   467             </td>
   468             <td>
   469               [ ease | linear | ease-in | ease-out | ease-in-out | step-start | step-end | steps(&lt;integer&gt;[, [ start | end ] ]?) | cubic-bezier(&lt;number&gt;, &lt;number&gt;, &lt;number&gt;, &lt;number&gt;) ] [, [ ease | linear | ease-in | ease-out | ease-in-out | step-start | step-end | steps(&lt;number&gt;[, [ start | end ] ]?) | cubic-bezier(&lt;number&gt;, &lt;number&gt;, &lt;number&gt;, &lt;number&gt;) ] ]*
   470             </td>
   471           </tr>
   472           <tr>
   473             <td>
   474               <em>Initial:</em>
   475             </td>
   476             <td>
   477               ease
   478             </td>
   479           </tr>
   480           <tr>
   481             <td>
   482               <em>Applies&nbsp;to:</em>
   483             </td>
   484             <td>
   485               all elements, :before and :after pseudo elements
   486             </td>
   487           </tr>
   488           <tr>
   489             <td>
   490               <em>Inherited:</em>
   491             </td>
   492             <td>
   493               no
   494             </td>
   495           </tr>
   496           <tr>
   497             <td>
   498               <em>Percentages:</em>
   499             </td>
   500             <td>
   501               N/A
   502             </td>
   503           </tr>
   504           <tr>
   505             <td>
   506               <em>Media:</em>
   507             </td>
   508             <td>
   509               interactive
   510             </td>
   511           </tr>
   512           <tr>
   513             <td>
   514               <em>Computed value:</em>
   515             </td>
   516             <td>
   517               Same as specified value.
   518             </td>
   519           </tr>
   520         </tbody>
   521       </table>
   522       <p>
   523         The timing functions have the following definitions.
   524       </p>
   525       <dl>
   526         <dt>
   527           ease
   528         </dt>
   529         <dd>
   530           The ease function is equivalent to cubic-bezier(0.25, 0.1, 0.25, 1.0).
   531         </dd>
   532         <dt>
   533           linear
   534         </dt>
   535         <dd>
   536           The linear function is equivalent to cubic-bezier(0.0, 0.0, 1.0, 1.0).
   537         </dd>
   538         <dt>
   539           ease-in
   540         </dt>
   541         <dd>
   542           The ease-in function is equivalent to cubic-bezier(0.42, 0, 1.0, 1.0).
   543         </dd>
   544         <dt>
   545           ease-out
   546         </dt>
   547         <dd>
   548           The ease-out function is equivalent to cubic-bezier(0, 0, 0.58, 1.0).
   549         </dd>
   550         <dt>
   551           ease-in-out
   552         </dt>
   553         <dd>
   554           The ease-in-out function is equivalent to cubic-bezier(0.42, 0, 0.58, 1.0)
   555         </dd>
   556         <dt>
   557           step-start
   558         </dt>
   559         <dd>
   560           The step-start function is equivalent to steps(1, start).
   561         </dd>
   562         <dt>
   563           step-end
   564         </dt>
   565         <dd>
   566           The step-end function is equivalent to steps(1, end).
   567         </dd>
   568         <dt>
   569           steps(&lt;integer&gt;[, [ start | end ] ]?)
   570         </dt>
   571         <dd>
   572           Specifies a stepping function, described above, taking two
   573           parameters. The first parameter specifies the number of intervals
   574           in the function. It must be a positive integer (greater than 0).
   575           The second parameter, which is optional, is
   576           either the value 'start' or 'end', and specifies the point
   577           at which the change of values occur within the interval.
   578           If the second parameter is omitted, it is given the value 'end'.
   579         </dd>
   580         <dt>
   581           cubic-bezier(&lt;number&gt;, &lt;number&gt;, &lt;number&gt;, &lt;number&gt;)
   582         </dt>
   583         <dd>
   584           Specifies a <a
   585           href="http://en.wikipedia.org/wiki/B%C3%A9zier_curve">cubic-bezier
   586           curve</a>. The four values specify points P<sub>1</sub> and
   587           P<sub>2</sub> of the curve as (x1, y1, x2, y2). Both x values must be
   588           in the range [0, 1] or the definition is invalid. The y values can
   589           exceed this range.
   590         </dd>
   591       </dl><!-- ======================================================================================================= -->
   592       <h3 id=transition-delay-property><a id=the-transition-delay-property->
   593         The <code class="property">'transition-delay'</code> Property
   594       </a></h3>
   595       <p>
   596         The <code class="property">'transition-delay'</code> property defines when the transition will start. It allows a transition to begin execution some some period of time from when it is applied. A <code class="property">'transition-delay'</code> value of '0s' means the transition will execute as soon as the property is changed. Otherwise, the value specifies an offset from the moment the property is changed, and the transition will delay execution by that offset.
   597       </p>
   598       <p>
   599         If the value for <code class="property">'transition-delay'</code> is a negative time offset then the transition will execute the moment the property is changed, but will appear to have begun execution at the specified offset. That is, the transition will appear to begin part-way through its play cycle. In the case where a transition has implied starting values and a negative <code class="property">'transition-delay'</code>, the starting values are taken from the moment the property is changed.
   600       </p>
   601       <table class="propdef">
   602         <tbody>
   603           <tr>
   604             <td>
   605               <em>Name:</em>
   606             </td>
   607             <td>
   608               <dfn id="transition-delay">transition-delay</dfn>
   609             </td>
   610           </tr>
   611           <tr>
   612             <td>
   613               <em>Value:</em>
   614             </td>
   615             <td>
   616               &lt;time&gt; [, &lt;time&gt;]*
   617             </td>
   618           </tr>
   619           <tr>
   620             <td>
   621               <em>Initial:</em>
   622             </td>
   623             <td>
   624               0s
   625             </td>
   626           </tr>
   627           <tr>
   628             <td>
   629               <em>Applies&nbsp;to:</em>
   630             </td>
   631             <td>
   632               all elements, :before and :after pseudo elements
   633             </td>
   634           </tr>
   635           <tr>
   636             <td>
   637               <em>Inherited:</em>
   638             </td>
   639             <td>
   640               no
   641             </td>
   642           </tr>
   643           <tr>
   644             <td>
   645               <em>Percentages:</em>
   646             </td>
   647             <td>
   648               N/A
   649             </td>
   650           </tr>
   651           <tr>
   652             <td>
   653               <em>Media:</em>
   654             </td>
   655             <td>
   656               interactive
   657             </td>
   658           </tr>
   659           <tr>
   660             <td>
   661               <em>Computed value:</em>
   662             </td>
   663             <td>
   664               Same as specified value.
   665             </td>
   666           </tr>
   667         </tbody>
   668       </table><!-- ======================================================================================================= -->
   669       <h3 id=transition-shorthand-property><a id=the-transition-shorthand-property->
   670         The <code class="property">'transition'</code> Shorthand Property
   671       </a></h3>
   672       <p>
   673         The <code class="property">'transition'</code> shorthand property combines the four properties described above into a single property.
   674       </p>
   675       <p>
   676         Note that order is important in this property. The first value that can be
   677         parsed as a time is assigned to the transition-duration. The second value that
   678         can be parsed as a time is assigned to transition-delay.
   679       </p>
   680       <p class="issue">
   681         An alternative proposal is to accept the font shorthand approach of
   682         using a "/" character between the values of the same type. e.g. 2s/4s would
   683         mean a duration of 2 seconds and a delay of 4 seconds.
   684       </p>
   685       <table class="propdef">
   686         <tbody>
   687           <tr>
   688             <td>
   689               <em>Name:</em>
   690             </td>
   691             <td>
   692               <dfn id="transition">transition</dfn>
   693             </td>
   694           </tr>
   695           <tr>
   696             <td>
   697               <em>Value:</em>
   698             </td>
   699             <td>
   700               [&lt;'transition-property'&gt; || &lt;'transition-duration'&gt; || &lt;'transition-timing-function'&gt; || &lt;'transition-delay'&gt; [, [&lt;'transition-property'&gt; || &lt;'transition-duration'&gt; || &lt;'transition-timing-function'&gt; || &lt;'transition-delay'&gt;]]*
   701             </td>
   702           </tr>
   703           <tr>
   704             <td>
   705               <em>Initial:</em>
   706             </td>
   707             <td>
   708               see individual properties
   709             </td>
   710           </tr>
   711           <tr>
   712             <td>
   713               <em>Applies&nbsp;to:</em>
   714             </td>
   715             <td>
   716               all elements, :before and :after pseudo elements
   717             </td>
   718           </tr>
   719           <tr>
   720             <td>
   721               <em>Inherited:</em>
   722             </td>
   723             <td>
   724               no
   725             </td>
   726           </tr>
   727           <tr>
   728             <td>
   729               <em>Percentages:</em>
   730             </td>
   731             <td>
   732               N/A
   733             </td>
   734           </tr>
   735           <tr>
   736             <td>
   737               <em>Media:</em>
   738             </td>
   739             <td>
   740               interactive
   741             </td>
   742           </tr>
   743           <tr>
   744             <td>
   745               <em>Computed value:</em>
   746             </td>
   747             <td>
   748               Same as specified value.
   749             </td>
   750           </tr>
   751         </tbody>
   752       </table>
   754       <h2 id="starting">
   755         Starting of transitions
   756       </h2>
   758       <p>
   759         When the computed value of an animatable property changes,
   760         implementations must decide what transitions to start based on
   761         the values of the 'transition-property', 'transition-duration',
   762         'transition-timing-function', and 'transition-delay' properties
   763         at the time the animatable property would first have its new
   764         computed value.
   765       </p>
   766       <div class="example" id="manual-reversing-example">
   767         <p style="display:none">
   768           Example(s):
   769         </p>
   770         <p>This provides a way for authors to specify different values
   771         of the 'transition-*' properties for the &ldquo;forward&rdquo;
   772         and &ldquo;reverse&rdquo; transitions (but see <a
   773         href="#reversing">below</a> for special reversing behavior when
   774         an <em>incomplete</em> transition is interrupted).  Authors can
   775         specify the value of 'transition-duration',
   776         'transition-timing-function', or 'transition-delay' in the same
   777         rule where they specify the value that triggers the transition,
   778         or can change these properties at the same time as they change
   779         the property that triggers the transition.  Since it's the new
   780         values of these 'transition-*' properties that affect the
   781         transition, these values will be used for the transitions
   782         <em>to</em> the associated transitioning values.  For example:
   783          </p>
   784         <pre>li {
   785   transition: background-color linear 1s;
   786   background: blue;
   787 }
   788 li:hover {
   789   background-color: green;
   790   transition-duration: 2s; /* applies to the transition *to* the :hover state */
   791 }</pre>
   792         <p>
   793           When a list item with these style rules enters the :hover
   794           state, the computed 'transition-duration' at the time that
   795           'background-color' would have its new value ('green') is '2s',
   796           so the transition from 'blue' to 'green' takes 2 seconds.
   797           However, when the list item leaves the :hover state, the
   798           transition from 'green' to 'blue' takes 1 second.
   799         </p>
   800       </div>
   802       <p>
   803         When the computed value of a property changes, implementations
   804         must start transitions based on the relevant item (see <a
   805         href="#transition-property">the definition of
   806         'transition-property'</a>) in the computed value of
   807         'transition-property'.
   808         Corresponding to this item there are
   809         computed values of 'transition-duration' and 'transition-delay'
   810         (see <a href="#list-matching">the rules on matching lists</a>).
   811         Define the <dfn>combined duration</dfn> of the transition
   812         as the sum of max('transition-duration', '0s') and 'transition-delay'.
   813         When the combined duration is greater than '0s',
   814         then a transition starts based on the values of
   815         'transition-duration', 'transition-delay',
   816         and 'transition-timing-function';
   817         in other cases transitions do not occur.
   818       </p>
   820       <p>
   821         Since this specification does not define
   822         when computed values change, and thus what changes to
   823         computed values are considered simultaneous,
   824         authors should be aware that changing any of the transition
   825         properties a small amount of time after making a change that
   826         might transition can result in behavior that varies between
   827         implementations, since the changes might be considered
   828         simultaneous in some implementations but not others.
   829       </p>
   830       <p class="note">Say something about simultaneity</p>
   832       <p>
   833         Once the transition of a property has started, it must continue
   834         running based on the original timing function, duration, and
   835         delay, even if the 'transition-timing-function',
   836         'transition-duration', or 'transition-delay' property changes
   837         before the transition is complete.  However, if the
   838         'transition-property' property changes such that the transition
   839         would not have started, the transition must stop (and the
   840         property must immediately change to its final value).
   841       </p>
   843       <p>
   844         Implementations must not start a transition when the computed
   845         value of a property changes as a result of declarative animation
   846         (as opposed to scripted animation).
   847       </p>
   849       <p>
   850         Implementations also must not start a transition when the
   851         computed value changes because it is inherited (directly or
   852         indirectly) from another element that is transitioning the same
   853         property.
   854       </p>
   856       <h2 id="reversing">
   857         Automatically reversing interrupted transitions
   858       </h2>
   859       <p>
   860         A common type of transition effect is when a running transition is
   861         interrupted and the property is reset to its original value. An
   862         example is a hover effect on an element, where the pointer enters and
   863         exits the element before the effect has completed. If the outgoing and
   864         incoming transitions are executed using their specified durations and
   865         timing functions, the resulting effect can be distractingly
   866         asymmetric. Instead, the expected behavior is that the new transition
   867         should be the reverse of what has already executed.
   868       </p>
   870       <p>
   871         If a running transition with duration T, executing so far for duration TE, 
   872         from state A, to state B, is interrupted by
   873         a property change that would start a new transition back to state A, and
   874         all the transition attributes are the same (duration, delay and timing function),
   875         then the new transition must reverse the effect. The new transition must:
   876       </p>
   878       <ol>
   879         <li>
   880           Use the B and A states as its "from" and "to" states respectively. It
   881           does not use the current value as its from state, due to the rules below.
   882         </li>
   883         <li>
   884           Execute with the same duration T, but starting as if the transition had
   885           already begun, without any transition delay, at the moment which would
   886           cause the new transition to finish in TE from the moment of interruption. In other
   887           words, the new transition will execute as if it started T-TE in the past.
   888         </li>
   889         <li>
   890           Use a timing function that is the portion of the curve traversed up
   891           to the moment of interruption, followed in the opposite direction (towards
   892           the starting point). This will make the transition appear as if it 
   893           is playing backwards.
   894         </li>
   895         <li>
   896           Ignore any transition delay.
   897         </li>
   898       </ol>
   900       <p>
   901         For example, suppose there is a transition with a duration of two
   902         seconds. If this transition is interrupted after 0.5 seconds and the
   903         property value assigned to the original value, then the new transition
   904         effect will be the reverse of the original, as if it had begun
   905         1.5 seconds in the past.
   906       </p>
   908       <p>
   909         Note that by using the defined from and to states for the reversing
   910         transition, it is also possible that it may reverse again, if
   911         interrupted; for example, if the transition reversing to state A was
   912         again interrupted by a property change to state B.
   913       </p>
   915       <p class="issue">Issue:
   916         This introduces the concept of reversing a timing function,
   917         which the spec has otherwise resisted doing, and also introduces
   918         a discontinuity between transitions that have
   919         almost completed (which get automatically reversed and thus have
   920         their timing function reversed) and transitions that have fully
   921         completed (where the reversal doesn't lead to the timing
   922         function being reversed).  An alternative proposal that avoids
   923         this is to follow the normal timing function algorithm, except
   924         multiply the duration (and also shorten any negative delay) by
   925         the (output) value of the transition timing function of the
   926         incomplete transition at the time it was interrupted, and, to
   927         account for multiple reverses in sequence, to divide by the
   928         shortening applied to the transition being interrupted.  For
   929         more details see this thread:
   930         <a href="http://lists.w3.org/Archives/Public/www-style/2009Nov/thread.html#msg302">November 2009 part</a>,
   931         <a href="http://lists.w3.org/Archives/Public/www-style/2009Dec/thread.html#msg319">December 2009 part</a>,
   932         <a href="http://lists.w3.org/Archives/Public/www-style/2010Jan/thread.html#msg136">January 2010 part</a>.
   933       </p>
   935       <h2 id=transition-events><a id=transition-events->
   936         Transition Events
   937       </a></h2>
   938       <p>
   939         The completion of a CSS Transition generates a corresponding <a href="http://www.w3.org/TR/DOM-Level-2-Events/events.html">DOM Event</a>.
   940         An event is fired for each property that undergoes a transition.
   941         This allows a content developer to perform actions that synchronize
   942         with the completion of a transition.
   943       </p>
   944       <p>
   945         Each event provides the name of the property the transition is
   946         associated with as well as the duration of the transition.
   947       </p>
   948       <dl>
   949         <dt>
   950           <b>Interface <i><a id="Events-TransitionEvent" name='Events-TransitionEvent'>TransitionEvent</a></i></b>
   951         </dt>
   952         <dd>
   953           <p>
   954             The <code>TransitionEvent</code> interface provides specific contextual information associated with transitions.
   955           </p>
   956           <dl>
   957             <dt>
   958               <b>IDL Definition</b>
   959             </dt>
   960             <dd>
   961               <div class='idl-code'>
   962                 <pre>
   963   interface TransitionEvent : Event {
   964     readonly attribute DOMString          propertyName;
   965     readonly attribute float              elapsedTime;
   966     readonly attribute DOMString          pseudoElement;
   967     void               initTransitionEvent(in DOMString typeArg, 
   968                                           in boolean canBubbleArg, 
   969                                           in boolean cancelableArg, 
   970                                           in DOMString propertyNameArg,
   971                                           in float elapsedTimeArg,
   972                                           in DOMString pseudoElementArg);
   973   };
   974   </pre>
   975               </div>
   976             </dd>
   977             <dt>
   978               <b>Attributes</b>
   979             </dt>
   980             <dd>
   981               <dl>
   982                 <dt>
   983                   <code class='attribute-name'><a id="Events-TransitionEvent-propertyName" name='Events-TransitionEvent-propertyName'>propertyName</a></code> of type <code>DOMString</code>, readonly
   984                 </dt>
   985                 <dd>
   986                   The name of the CSS property associated with the transition.
   987                 </dd>
   988               </dl>
   989               <dl>
   990                 <dt>
   991                   <code class='attribute-name'><a id="Events-TransitionEvent-elapsedTime" name='Events-TransitionEvent-elapsedTime'>elapsedTime</a></code> of type <code>float</code>, readonly
   992                 </dt>
   993                 <dd>
   994                   The amount of time the transition has been running, in seconds, when this event fired. Note that this value is not affected by the value of <code class="property">transition-delay</code>.
   995                 </dd>
   996               </dl>
   997               <dl>
   998                 <dt>
   999                   <code class='attribute-name'><a id="Events-TransitionEvent-pseudoElement" name='Events-TransitionEvent-pseudoElement'>pseudoElement</a></code> of type <code>DOMString</code>, readonly
  1000                 </dt>
  1001                 <dd>
  1002                   The name (beginning with two colons) of the CSS
  1003                   pseudo-element on which the transition occured (in
  1004                   which case the target of the event is that
  1005                   pseudo-element's corresponding element), or the empty
  1006                   string if the transition occurred on an element (which
  1007                   means the target of the event is that element).
  1008                 </dd>
  1009               </dl>
  1010             </dd>
  1011             <dt>
  1012               <b>Methods</b>
  1013             </dt>
  1014             <dd>
  1015               <dl>
  1016                 <dt>
  1017                   <code class='method-name'><a id="Events-TransitionEvent-initTransitionEvent" name='Events-TransitionEvent-initTransitionEvent'>initTransitionEvent</a></code>
  1018                 </dt>
  1019                 <dd>
  1020                   <div class='method'>
  1021                     The <code>initTransitionEvent</code> method is used to
  1022                     initialize the value of a <code>TransitionEvent</code>
  1023                     created through the <a
  1024                     href='http://www.w3.org/TR/DOM-Level-2-Events/events.html#Events-DocumentEvent'><code>DocumentEvent</code></a>
  1025                     interface. This method may only be called before the
  1026                     <code>TransitionEvent</code> has been dispatched via the
  1027                     <code>dispatchEvent</code> method, though it may be called
  1028                     multiple times during that phase if necessary. If called
  1029                     multiple times, the final invocation takes precedence.
  1030                     <p class="issue">Should new events being created still
  1031                     have init*Event methods?</p>
  1032                     <div class='parameters'>
  1033                       <b>Parameters</b>
  1034                       <div class='paramtable'>
  1035                         <dl>
  1036                           <dt>
  1037                             <code class='parameter-name'>typeArg</code> of type <code>DOMString</code>
  1038                           </dt>
  1039                           <dd>
  1040                             Specifies the event type.<br>
  1041                           </dd>
  1042                           <dt>
  1043                             <code class='parameter-name'>canBubbleArg</code> of type <code>boolean</code>
  1044                           </dt>
  1045                           <dd>
  1046                             Specifies whether or not the event can bubble.<br>
  1047                           </dd>
  1048                           <dt>
  1049                             <code class='parameter-name'>cancelableArg</code> of type <code>boolean</code>
  1050                           </dt>
  1051                           <dd>
  1052                             Specifies whether or not the event's default action can be prevented. Since a TransitionEvent
  1053                             is purely for notification, there is no default action.<br>
  1054                           </dd>
  1055                           <dt>
  1056                             <code class='parameter-name'>propertyNameArg</code> of type <code>DOMString</code>
  1057                           </dt>
  1058                           <dd>
  1059                             Specifies the name of the property associated with the <a href='http://www.w3.org/TR/DOM-Level-2-Events/events.html#Events-Event'><code>Event</code></a>.
  1060                             (See the <a href="#Events-TransitionEvent-propertyName">propertyName</a> attribute.)
  1061                           </dd>
  1062                           <dt>
  1063                             <code class='parameter-name'>elapsedTimeArg</code> of type <code>float</code>
  1064                           </dt>
  1065                           <dd>
  1066                             Specifies the amount of time, in seconds, the transition has been running at the time of initialization.
  1067                             (See the <a href="#Events-TransitionEvent-elapsedTime">elapsedTime</a> attribute.)
  1068                           </dd>
  1069                           <dt>
  1070                             <code class='parameter-name'>pseudoElementArg</code> of type <code>DOMString</code>
  1071                           </dt>
  1072                           <dd>
  1073                             Specifies the pseudo-element on which the
  1074                             transition occurred.
  1075                             (See the <a href="#Events-TransitionEvent-pseudoElement">pseudoElement</a> attribute.)
  1076                             <span class="issue">Does adding this additional argument create any compatibility problems?</span>
  1077                           </dd>
  1078                         </dl>
  1079                       </div>
  1080                     </div><!-- parameters -->
  1081                     <div>
  1082                       <b>No Return Value</b>
  1083                     </div>
  1084                     <div>
  1085                       <b>No Exceptions</b>
  1086                     </div>
  1087                   </div><!-- method -->
  1088                 </dd>
  1089               </dl>
  1090             </dd>
  1091           </dl>
  1092         </dd>
  1093       </dl>
  1094       <p>
  1095         There is one type of transition event available.
  1096       </p>
  1097       <dl>
  1098         <dt>
  1099           <b>transitionend</b>
  1100         </dt>
  1101         <dd>
  1102           The 'transitionend' event occurs at the completion of the transition. In the
  1103           case where a transition is removed before completion, such as if the
  1104           transition-property is removed, then the event will not fire.
  1105           <ul>
  1106             <li>Bubbles: Yes
  1107             </li>
  1108             <li>Cancelable: Yes
  1109             </li>
  1110             <li>Context Info: propertyName, elapsedTime
  1111             </li>
  1112           </ul>
  1113         </dd>
  1114       </dl>
  1116       <h2 id="animatable-types"><a id=animation-of-property-types->
  1117         Animation of property types
  1118       </a></h2>
  1120       <p>
  1121         When interpolating between two values,
  1122         <i>V</i><sub>start</sub> and <i>V</i><sub>end</sub>,
  1123         interpolation is done using the output <i>p</i> of the timing function,
  1124         which gives the portion of the value space
  1125         that the interpolation has crossed.
  1126         Thus the result of the interpolation is
  1127         <i>V</i><sub>res</sub> =
  1128           (1 - <i>p</i>) &sdot; <i>V</i><sub>start</sub> +
  1129           <i>p</i> &sdot; <i>V</i><sub>end</sub>.
  1130       </p>
  1132       <p>
  1133         The following describes how each property type undergoes transition or
  1134         animation.
  1135       </p>
  1137       <ul>
  1138         <li>
  1139           <strong>color</strong>: interpolated via red, green, blue and alpha
  1140           components (treating each as a number, see below).
  1141           <div class="issue">Issue: Are the colors interpolated in
  1142           premultiplied space or non-premultiplied space?</div>
  1143         </li>
  1144         <li>
  1145           <strong>length</strong>: interpolated as real numbers.
  1146         </li>
  1147         <li>
  1148           <strong>percentage</strong>: interpolated as real numbers.
  1149         </li>
  1150         <li>
  1151           <strong>integer</strong>: interpolated via discrete steps (whole
  1152           numbers). The interpolation happens in real number space and is
  1153           converted to an integer using <code>floor()</code>.
  1154           <span class="issue">
  1155             This floor behavior is inconsistent with SMIL Animation /
  1156             SVG Animation.
  1157           </span>
  1158         </li>
  1159         <li>
  1160           <strong>font weight</strong>: interpolated via discrete steps
  1161           (multiples of 100). The interpolation happens in real number
  1162           space and is converted to an integer by rounding to the
  1163           nearest multiple of 100.
  1164           <span class="issue">
  1165             This round-to-nearest behavior is inconsistent with the
  1166             floor behavior used for integer types, but probably should
  1167             be consistent (one way or the other).
  1168           </span>
  1169         </li>
  1170         <li>
  1171           <strong>number</strong>: interpolated as real (floating point)
  1172           numbers.
  1173         </li>
  1174         <li>
  1175           <strong>transform list</strong>: see 
  1176             CSS Transforms specification [[!CSS3-TRANSFORMS]].
  1177         </li>
  1178         <li>
  1179           <strong>rectangle</strong>: interpolated via the x, y,
  1180           width and height components (treating each as a number).
  1181         </li>
  1182         <li>
  1183           <strong>visibility</strong>: if one of the values is
  1184           'visible', interpolated as a discrete step where values of the
  1185           timing function between 0 and 1 map to 'visible' and other
  1186           values of the timing function (which occur only at the
  1187           start/end of the transition or as a result of 'cubic-bezier()'
  1188           functions with Y values outside of [0, 1]) map to the closer
  1189           endpoint; if neither value is 'visible' then not interpolable.
  1190         </li>
  1191         <li>
  1192           <strong>shadow</strong>: interpolated via the color, x, y
  1193           and blur components (treating them as color and numbers where
  1194           appropriate). In the case where there are lists of shadows,
  1195           the shorter list is padded at the end with shadows whose
  1196           color is transparent and all lengths (x, y, blur) are 0.
  1197         </li>
  1198         <li>
  1199           <strong>gradient</strong>: interpolated via the
  1200           positions and colors of each stop. They must have the same type
  1201           (radial or linear) and same number of stops in order to be animated.
  1202           <span class="note">Note: [[CSS3-IMAGES]] may extend this
  1203           definition.</span>
  1204         </li>
  1205         <li>
  1206           <strong>paint server</strong> (SVG): interpolation is only supported
  1207           between: gradient to gradient and color to color. They then
  1208           work as above.
  1209         </li>
  1210         <li>
  1211           <strong>list of above types</strong>: If the lists have the
  1212           same number of items, each item in the list is interpolated using the
  1213           rules above. Otherwise the interpolation is determined by the property
  1214           rules. If the property extends its list by repeating values, then this
  1215           repeated form will be used in the interpolation (<code class="property">'background-position'</code>
  1216           is an example of a property that would transition between lists of different lengths). If
  1217           the property does not allow extending its list, then no interpolation
  1218           will occur.
  1219         </li>
  1220         <li>
  1221           <strong>a shorthand property</strong>: If any part of a
  1222           shorthand can be animated, then interpolation is performed as
  1223           if those animatable properties were individually specified.
  1224         </li>
  1225       </ul>
  1227       <p class="issue">Issue:  Need to describe handling of out-of-range
  1228       values that can result from cubic-bezier().  Clamping values to the
  1229       allowed range is probably the best solution.</p>
  1231       <h2 id=animatable-properties><a id=animatable-properties->
  1232         Animatable properties
  1233       </a></h2>
  1235       <!--
  1236       As resolved in
  1237       http://lists.w3.org/Archives/Public/www-style/2011Sep/0497.html
  1238       -->
  1239       <p>For properties that exist at the time this specification was
  1240       developed, this specification defines whether and how they are
  1241       animated.  However, future CSS specifications may define
  1242       additional properties, additional values for existing properties,
  1243       or additional animation behavior of existing values.  In order to
  1244       describe new animation behaviors and to have the definition of
  1245       animation behavior in a more appropriate location, future CSS
  1246       specifications should include an "Animatable:" line in the summary
  1247       of the property's definition (in addition to the other lines
  1248       described in [[CSS21]], <a
  1249       href="http://www.w3.org/TR/CSS21/about.html#property-defs">section
  1250       1.4.2</a>).  This line should say "no" to indicate that a property
  1251       cannot be animated or should reference an animation behavior
  1252       (which may be one of the behaviors in the <a
  1253       href="#animation-of-property-types-">Animation of property
  1254       types</a> section above, or may be a new behavior) to define how
  1255       the property animates.  Such definitions override those given in
  1256       this specification.</p>
  1258       <h3 id=animatable-css><a id=properties-from-css->
  1259         Properties from CSS
  1260       </a></h3>
  1262      <table class="animatable-properties">
  1263        <tr>
  1264          <th>Property Name</th>
  1265          <th>Type</th>
  1266        </tr>
  1267        <tr>
  1268          <td>background-color</td><td>color</tr>
  1269        <tr>
  1270          <td>background-position</td><td>percentage, length</td>
  1271        </tr>
  1272        <tr>
  1273          <td>border-bottom-color</td><td>color</td>
  1274        </tr>
  1275        <tr>
  1276          <td>border-bottom-width</td><td>length</td>
  1277        </tr>
  1278        <tr>
  1279          <td>border-left-color</td><td>color</td>
  1280        </tr>
  1281        <tr>
  1282          <td>border-left-width</td><td>length</td>
  1283        </tr>
  1284        <tr>
  1285          <td>border-right-color</td><td>color</td>
  1286        </tr>
  1287        <tr>
  1288          <td>border-right-width</td><td>length</td>
  1289        </tr>
  1290        <tr>
  1291          <td>border-spacing</td><td>length</td>
  1292        </tr>
  1293        <tr>
  1294          <td>border-top-color</td><td>color</td>
  1295        </tr>
  1296        <tr>
  1297          <td>border-top-width</td><td>length</td>
  1298        </tr>
  1299        <tr>
  1300          <td>bottom</td><td>length, percentage</td>
  1301        </tr>
  1302        <tr>
  1303          <td>clip</td><td>rectangle</td>
  1304        </tr>
  1305        <tr>
  1306          <td>color</td><td>color</td>
  1307        </tr>
  1308        <tr>
  1309          <td>crop <span class="issue">css3-content will likely advance slower than this specification, in which case this definition should move there</span></td><td>rectangle</td>
  1310        </tr>
  1311        <tr>
  1312          <td>font-size</td><td>length, percentage</td>
  1313        </tr>
  1314        <tr>
  1315          <td>font-weight</td><td>font weight</td>
  1316        </tr>
  1317        <tr>
  1318          <td>height</td><td>length, percentage</td>
  1319        </tr>
  1320        <tr>
  1321          <td>left</td><td>length, percentage</td>
  1322        </tr>
  1323        <tr>
  1324          <td>letter-spacing</td><td>length</td>
  1325        </tr>
  1326        <tr>
  1327          <td>line-height</td><td>number, length, percentage</td>
  1328        </tr>
  1329        <tr>
  1330          <td>margin-bottom</td><td>length</td>
  1331        </tr>
  1332        <tr>
  1333          <td>margin-left</td><td>length</td>
  1334        </tr>
  1335        <tr>
  1336          <td>margin-right</td><td>length</td>
  1337        </tr>
  1338        <tr>
  1339          <td>margin-top</td><td>length</td>
  1340        </tr>
  1341        <tr>
  1342          <td>max-height</td><td>length, percentage</td>
  1343        </tr>
  1344        <tr>
  1345          <td>max-width</td><td>length, percentage </td>
  1346        </tr>
  1347        <tr>
  1348          <td>min-height</td><td>length, percentage</td>
  1349        </tr>
  1350        <tr>
  1351          <td>min-width</td><td>length, percentage</td>
  1352        </tr>
  1353        <tr>
  1354          <td>opacity</td><td>number</td>
  1355        </tr>
  1356        <tr>
  1357          <td>outline-color</td><td>color</td>
  1358        </tr>
  1359        <tr>
  1360          <td>outline-offset</td><td>integer</td>
  1361        </tr>
  1362        <tr>
  1363          <td>outline-width</td><td>length</td>
  1364        </tr>
  1365        <tr>
  1366          <td>padding-bottom</td><td>length</td>
  1367        </tr>
  1368        <tr>
  1369          <td>padding-left</td><td>length</td>
  1370        </tr>
  1371        <tr>
  1372          <td>padding-right</td><td>length</td>
  1373        </tr>
  1374        <tr>
  1375          <td>padding-top</td><td>length</td>
  1376        </tr>
  1377        <tr>
  1378          <td>right</td><td>length, percentage</td>
  1379        </tr>
  1380        <tr>
  1381          <td>text-indent</td><td>length, percentage</td>
  1382        </tr>
  1383        <tr>
  1384          <td>text-shadow</td><td>shadow</td>
  1385        </tr>
  1386        <tr>
  1387          <td>top</td><td>length, percentage</td>
  1388        </tr>
  1389        <tr>
  1390          <td>vertical-align</td><td>length, percentage</td>
  1391        </tr>
  1392        <tr>
  1393          <td>visibility</td><td>visibility</td>
  1394        </tr>
  1395        <tr>
  1396          <td>width</td><td>length, percentage</td>
  1397        </tr>
  1398        <tr>
  1399          <td>word-spacing</td><td>length, percentage</td>
  1400        </tr>
  1401        <tr>
  1402          <td>z-index</td><td>integer</td>
  1403        </tr>
  1404      </table>
  1406 <p class="issue">
  1407   This list omits the following properties that Gecko can animate, and
  1408   which likely should be included:
  1409   background-size,
  1410   border-*-radius,
  1411   box-shadow,
  1412   column-count,
  1413   column-gap,
  1414   column-rule-color,
  1415   column-rule-width,
  1416   column-width,
  1417   font-size-adjust,
  1418   font-stretch,
  1419   marker-offset,
  1420   text-decoration-color,
  1421   transform,
  1422   transform-origin.
  1423 </p>
  1425      <h3 id=animatable-svg><a id=properties-from-svg->
  1426        Properties from SVG
  1427      </a></h3>
  1429      <p>
  1430        All properties defined as animatable in the SVG specification, provided
  1431        they are one of the property types listed above.
  1432       </p>
  1434      <!-- <table>
  1435        <tr>
  1436          <th>Property Name</th><th>Type</th>
  1437        </tr>
  1438        <tr>
  1439          <td>stop-color</td><td>color</td>
  1440        </tr>
  1441        <tr>
  1442          <td>stop-opacity</td><td>float</td>
  1443        </tr>
  1444        <tr>
  1445          <td>fill</td><td>paint server</td>
  1446        </tr>
  1447        <tr>
  1448          <td>fill-opacity</td><td>float</td>
  1449        </tr>
  1450        <tr>
  1451          <td>stroke</td><td>paint server</td>
  1452        </tr>
  1453        <tr>
  1454          <td>stroke-dasharray</td><td>list of numbers</td>
  1455        </tr>
  1456        <tr>
  1457          <td>stroke-dashoffset</td><td>number</td>
  1458        </tr>
  1459        <tr>
  1460          <td>stroke-miterlimit</td><td>number</td>
  1461        </tr>
  1462        <tr>
  1463          <td>stroke-opacity</td><td>float</td>
  1464        </tr>
  1465        <tr>
  1466          <td>stroke-width</td><td>float</td>
  1467        </tr>
  1468        <tr>
  1469          <td>viewport-fill</td><td>color</td>
  1470        </tr>
  1471        <tr>
  1472          <td>viewport-fill-opacity</td><td>color</td>
  1473        </tr>
  1474       </table> -->
  1476 <h2 id="acknowledgments">Acknowledgments</h2>
  1478 <p>Thanks especially to the feedback from
  1479 Tab Atkins,
  1480 Aryeh Gregor,
  1481 Vincent Hardy,
  1482 Cameron McCormack,
  1483 Alex Mogilevsky,
  1484 and all the rest of the
  1485 <a href="http://lists.w3.org/Archives/Public/www-style/">www-style</a> community.</p>
  1487 <h2 id="references">References</h2>
  1489 <h3 class="no-num" id=normative-references>Normative references</h3>
  1490 <!--normative-->
  1492 <h3 class="no-num" id=other-references>Other references</h3>
  1493 <!--informative-->
  1497 <h2 class="no-num" id=property-index>Property index</h2>
  1498 <!-- properties -->
  1502 <h2 class="no-num" id="index">Index</h2>
  1503 <!--index-->
  1505 </body>
  1506 </html>
  1507 <!-- Keep this comment at the end of the file
  1508 Local variables:
  1509 mode: sgml
  1510 sgml-default-doctype-name:"html"
  1511 sgml-minimize-attributes:t
  1512 End:
  1513 -->

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