当子元素处于浮动状态时，设置负margin，子元素会叠盖到兄弟元素之上* {box-sizing: border-box;}

html, body{width: 100%;height: 100%;margin: 0;padding: 0;}

.container{width:1300px; margin: 0 auto; border:1px solid #000;}

.container:after{display: table;content:"";clear:both;}

.left{width:100%;background: blue; text-align: center;float:left;border: 1px solid red;height: 200px;}

.center{width: 320px;margin-left:-100%;background: white;float:left;border: 1px solid red;height: 200px;}

.right{width: 290px;margin-left:-290px;background-color: yellow;float:left;border: 1px solid red;height: 200px;}

<div class="center">center 320 黑框</div>

<div class="right">right</div>

</div>

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css布局之圣杯布局