三栏等高 .Middle, .Left, .Right { float: left;

三栏等高
     .Middle, .Left, .Right
        {
            float: left;
            padding-bottom: 32767px;
            margin-bottom: -32767px;
        }
什么作用<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>三栏等高(wwww.hemin.cn)</title>
    <style type="text/css">
        .Middle, .Left, .Right
        {
            float: left;
            padding-bottom: 32767px;
            margin-bottom: -32767px;
        }
        .Content
        {
            overflow: hidden;
            padding: 0 250px 0 300px;
            zoom: 1;
            position: relative;
        }
        .Middle
        {
            background: #090;
            width: 100%;
        }
        .Left
        {
            background: #333;
            width: 300px;
            margin-left: -100%;
            position: relative;
            right: 300px;
            _left: 250px;
        }
        .Right
        {
            background: #666;
            width: 250px;
            margin-right: -100%;
        }
    </style>
</head>
<body>
    <div class="Content">
        <div class="Middle">
            中间</div>
        <div class="Left">左边
        </div>
        <div class="Right">右边
        </div>
    </div>
</body>
</html>