案例：CSS3案例     状态：可编辑再运行    进入竖版
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<!DOCTYPE html>
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<html>
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<head>
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<style>
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div
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{
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width:100px;
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height:100px;
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background:red;
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position:relative;
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animation:myfirst 5s linear 2s infinite alternate;
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/* Firefox: */
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-moz-animation:myfirst 5s linear 2s infinite alternate;
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/* Safari and Chrome: */
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-webkit-animation:myfirst 5s linear 2s infinite alternate;
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/* Opera: */
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-o-animation:myfirst 5s linear 2s infinite alternate;
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}
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​
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@keyframes myfirst
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{
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0%   {background:red; left:0px; top:0px;}
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25%  {background:yellow; left:200px; top:0px;}
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50%  {background:blue; left:200px; top:200px;}
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75%  {background:green; left:0px; top:200px;}
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100% {background:red; left:0px; top:0px;}
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}
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​
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@-moz-keyframes myfirst /* Firefox */
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{
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0%   {background:red; left:0px; top:0px;}
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25%  {background:yellow; left:200px; top:0px;}
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50%  {background:blue; left:200px; top:200px;}
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75%  {background:green; left:0px; top:200px;}
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100% {background:red; left:0px; top:0px;}
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}
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​
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@-webkit-keyframes myfirst /* Safari and Chrome */
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{
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0%   {background:red; left:0px; top:0px;}
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25%  {background:yellow; left:200px; top:0px;}
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50%  {background:blue; left:200px; top:200px;}
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75%  {background:green; left:0px; top:200px;}
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100% {background:red; left:0px; top:0px;}
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}
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​
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@-o-keyframes myfirst /* Opera */
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{