两列布局（左侧宽度固定，右侧自适应）
例如：
<!doctype html><html><head><title>左部宽度固定，右部自适应</title><meta charset="utf-8"/><style type="text/css"> *{ margin:0px; padding:0px; font-size:14px; } div{ height:600px; } .left{ width:300px; background:red; float:left; } body div.right{ background:green; margin-left:300px; }</style> <link rel="stylesheet" type="text/css" href=""/></head><body> <div class="left">左部</div> <div class="right">右部</div></body></html>三列布局，（左右宽度固定，中间自适应）；
<!doctype html><html><head><title>左右宽度固定，中间自适应</title><meta charset="utf-8"/><style type="text/css"> *{ margin:0px; padding:0px; font-size:14px; } div{ height:700px; } .left{ width:300px; background:red; float:left; } .right{ width:400px; background:yellow; float:right; } .center{ background:blue; margin:0 400px 0 300px; }</style></head><body><div class="left">左</div><div class="right">右</div><div class="center">中</div></body></html>
