CSS布局 上下固定 中左固定，主体内容自动填充
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>两列式全屏布局</title>
<style type="text/css">
html, body {
margin: 0;
padding: 0;
}
.top {
border: solid 1px black;
margin: 0 0 5px 0;
height: 50px;
}
.sidebar {
position: absolute;
left: 0;
top: 57px;
width: 205px;
background-color: yellow;
border: solid 1px black;
border-left-width: 0;
height: 50px;
}
.main {
margin-left: 210px;
border: solid 1px black;
height: 50px;
}
</style>
</head>
<body>
<div class="top">A(固定高度，宽度自适应)</div>
<div class="sidebar">B(高度任意，宽度为固定)</div>
<div class="main">C(高度任意，宽度为除开B之外的所有空间，自适应)</div>
</body>
</html>
