先看代码
<head> <meta charset="UTF-8"> <title>Document</title> <style> .outer { width: 300px; height: 600px; background: #888; } .b169 { width: 100%; height: 0; padding-bottom: 56.2%; position: relative; } .b169 > .innerb169 { width: 100%; height: 100%; background-color: red; position: absolute; } </style> </head> <body> <script type="text/javascript"> </script> <div class="outer"> <div class="b169"> <div class="innerb169">hello</div> </div> </div> </body>
要查一下资料了。规定基于父元素的宽度的百分比的内边距。