<body>
<div class="aside">
这是 side
</div>
<div class="main">
这是 main
</div>
</body>
body,html{
height: 100%;
color: #fff
}
.aside {
width: 300px;
height: 100%;
float: left;
background: #f66;
}
.main {
height: 100%;
background: #000;
}