如下代码实现方块在限定区域内不停弹跳。
<!DOCTYPE html> <html> <head> <style> div { width:100px; height:100px; background:red; position:relative; animation:myfirst 5s linear 2s infinite alternate; /* Firefox: */ -moz-animation:myfirst 5s linear 2s infinite alternate; /* Safari and Chrome: */ -webkit-animation:myfirst 5s linear 2s infinite alternate; /* Opera: */ -o-animation:myfirst 5s linear 2s infinite alternate; } @keyframes myfirst { 0% {background:red; left:0px; top:0px;} 25% {background:yellow; left:200px; top:0px;} 50% {background:blue; left:200px; top:200px;} 75% {background:green; left:0px; top:200px;} 100% {background:red; left:0px; top:0px;} } @-moz-keyframes myfirst /* Firefox */ { 0% {background:red; left:0px; top:0px;} 25% {background:yellow; left:200px; top:0px;} 50% {background:blue; left:200px; top:200px;} 75% {background:green; left:0px; top:200px;} 100% {background:red; left:0px; top:0px;} } @-webkit-keyframes myfirst /* Safari and Chrome */ { 0% {background:red; left:0px; top:0px;} 25% {background:yellow; left:200px; top:0px;} 50% {background:blue; left:200px; top:200px;} 75% {background:green; left:0px; top:200px;} 100% {background:red; left:0px; top:0px;} } @-o-keyframes myfirst /* Opera */ { 0% {background:red; left:0px; top:0px;} 25% {background:yellow; left:200px; top:0px;} 50% {background:blue; left:200px; top:200px;} 75% {background:green; left:0px; top:200px;} 100% {background:red; left:0px; top:0px;} } </style> </head> <body> <p><b>注意:</b> 该实例在 Internet Explorer 9 及更早 IE 版本是无效的。</p> <div></div> </body> </html>