CSS代码：
*{ margin: 0;
padding: 0;
list-style: none;}body{ width: 100%;
height: 100%;}#nav{ position: relative;
width: 100%;
height:80px;
background: #fff;}#logo_wrap{ width: auto;
height: 100%;
margin-left: 73px;}#logo_img{ float: left;
width: 54px;
height: 54px;
margin-top: 13px;
background: #ccc;}#logo_text{ float: left;
width: auto;
font-size: 22px;
height: 54px;
line-height: 54px;
margin-top: 13px;
margin-left: 20px;
color:rgb(56,148,227);
font-family: Fantasy;
font-weight: bolder;}#mainbody{ position: absolute;
width: 100%;
height: calc(100% - 80px); //设置为父元素body的100%减去nav盒子的高度80px
background: #ccc;}