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<!DOCTYPE html>
<html>
<head>
<style> 
div
{
width:100px;
height:50px;
background:red;
color:white;
font-weight:bold;
transition:width 2s;
-moz-transition:width 2s; /* Firefox 4 */
-webkit-transition:width 2s; /* Safari and Chrome */
-o-transition:width 2s; /* Opera */
}

#div1 {transition-timing-function: linear;}
#div2 {transition-timing-function: ease;}
#div3 {transition-timing-function: ease-in;}
#div4 {transition-timing-function: ease-out;}
#div5 {transition-timing-function: ease-in-out;}

/* Firefox 4: */
#div1 {-moz-transition-timing-function: linear;}
#div2 {-moz-transition-timing-function: ease;}
#div3 {-moz-transition-timing-function: ease-in;}
#div4 {-moz-transition-timing-function: ease-out;}
#div5 {-moz-transition-timing-function: ease-in-out;}

/* Safari and Chrome: */
#div1 {-webkit-transition-timing-function: linear;}
#div2 {-webkit-transition-timing-function: ease;}
#div3 {-webkit-transition-timing-function: ease-in;}
#div4 {-webkit-transition-timing-function: ease-out;}
#div5 {-webkit-transition-timing-function: ease-in-out;}

/* Opera: */
#div1 {-o-transition-timing-function: linear;}
#div2 {-o-transition-timing-function: ease;}
#div3 {-o-transition-timing-function: ease-in;}
#div4 {-o-transition-timing-function: ease-out;}
#div5 {-o-transition-timing-function: ease-in-out;}

div:hover
{
width:300px;
}
</style>
</head>
<body>

<div id="div1" style="top:100px">linear</div>
<div id="div2" style="top:150px">ease</div>
<div id="div3" style="top:200px">ease-in</div>
<div id="div4" style="top:250px">ease-out</div>
<div id="div5" style="top:300px">ease-in-out</div>

<p>请把鼠标指针移动到红色的 div 元素上，就可以看到过渡效果。</p>

<p><b>注释：</b>本例在 Internet Explorer 中无效。</p>

</body>
</html>

W3School TIY Editor