animation:mymove 5s infinite;
-moz-animation:mymove 5s infinite;
-webkit-animation:mymove 5s infinite;
-o-animation:mymove 5s infinite;
0% {top:0px; background:red; width:100px;}
100% {top:200px; background:yellow; width:300px;}
0% {top:0px; background:red; width:100px;}
100% {top:200px; background:yellow; width:300px;}
@-webkit-keyframes mymove
0% {top:0px; background:red; width:100px;}
100% {top:200px; background:yellow; width:300px;}
0% {top:0px; background:red; width:100px;}
100% {top:200px; background:yellow; width:300px;}
<p><b>注释:</b>本例在 Internet Explorer 中无效。</p>