float布局

圣杯布局和双飞翼布局的目的

1、三栏布局，中间一栏最先加载和渲染（内容最重要）
2、两侧内容固定，中间内容随着宽度自适应
3、一般用于PC网页

圣杯布局和双飞翼布局的技术总结

1、使用float布局
2、两侧使用margin负值，以便和中间内容横向重叠
3、防止中间内容被两侧覆盖，一个用padding 一个用margin

一、圣杯布局

<style type="text/css">
        body {
            min-width: 550px;
        }
        #header {
            text-align: center;
            background-color: #f1f1f1;
        }

        #container {
            padding-left: 200px;
            padding-right: 150px;
        }
        #container .column {
            float: left;
        }

        #center {
            background-color: #ccc;
            width: 100%;
        }
        #left {
            position: relative;
            background-color: yellow;
            width: 200px;
            margin-left: -100%;
            right: 200px;
        }
        #right {
            background-color: red;
            width: 150px;
            margin-right: -150px;
        }

        #footer {
            text-align: center;
            background-color: #f1f1f1;
        }

        /* 手写 clearfix */
        .clearfix:after {
            content: '';
            display: block;
            height:0;
            visibility: hidden;
            clear: both;
        }
    </style>
<div id="header">this is header</div>
    <div id="container" class="clearfix">
        <div id="center" class="column">this is center</div>
        <div id="left" class="column">this is left</div>
        <div id="right" class="column">this is right</div>
    </div>
<div id="footer">this is footer</div>

二、双飞翼布局

<style type="text/css">
        body {
            min-width: 550px;
        }
        .col {
            float: left;
        }

        #main {
            width: 100%;
            height: 200px;
            background-color: #ccc;
        }
        #main-wrap {
            margin: 0 190px 0 190px;
        }

        #left {
            width: 190px;
            height: 200px;
            background-color: #0000FF;
            margin-left: -100%;
        }
        #right {
            width: 190px;
            height: 200px;
            background-color: #FF0000;
            margin-left: -190px;
        }
    </style>
    
    <div id="main" class="col">
        <div id="main-wrap">
            this is main
        </div>
    </div>
    <div id="left" class="col">
        this is left
    </div>
    <div id="right" class="col">
        this is right
    </div>

三、手写clearfix

.clearfix:after {
	content: ' ';
	height: 0;
	display: block;
	visibility: hidden;
	clear: both;
}
.clearfix {
	*zoom: 1;        /*兼容 IE 低版本*/
}