| 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106 | <!DOCTYPE html><html lang="en"><head>  <meta charset="UTF-8">  <meta http-equiv="X-UA-Compatible" content="IE=edge">  <meta name="viewport" content="width=device-width, initial-scale=1.0">  <title>Document</title>  <style>    * {      margin: 0;      padding: 0;    }    h3 {      width: 960px;      height: 50px;      background: #cccccc;      text-align: center;      line-height: 50px;      margin: 0 auto 10px;    }    #imgBox {      width: 960px;      height: 550px;      background: url(img/1.jpg) 0 0 no-repeat;      background-size: 100% 100%;      margin: 0 auto;    }    #content {      width: 960px;      margin: 10px auto;      overflow: hidden;    }    #left {      width: 630px;      height: 300px;      background: red;      float: left;    }    #right {      width: 300px;      height: 300px;      background: blue;      float: right;    }    @media screen and (max-width: 960px) {      h3 {        width: 100%;      }      #imgBox {        width: 100%;        background-image:  url(img/2.jpg);        padding-top: 56%;        height: 0;        /* background-size: cover; */        /*         960  540         100  56%        */      }      #content {        width: 100%;      }      #left {        width: 65%;      }      #right {        width: 33%;      }    }    @media screen and (max-width: 480px) {      #left{        width: 100%;      }      #right{        width: 100%;      }      #imgBox{        background-image: url(img/3.jpg);      }    }  </style></head><body>  <h3>页眉</h3>  <h3>导航</h3>  <div id="imgBox"></div>  <div id="content">    <div id="left"></div>    <div id="right"></div>  </div>  <h3>页脚</h3></body></html>
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