圣杯/双飞翼布局与负边距

左右定宽，中间自适应，利用负边距来改变文档流

圣杯布局

htmlCopy
<div class="content">
  <div class="middle"></div>
  <div class="left"></div>
  <div class="right"></div>
</div>

cssCopy
.content {
  overflow: hidden;
  padding: 0 100px;
}

.middle {
  position: relative;
  width: 100%;
  float: left;
  height: 80px;
  background: #f00;
}

.left {
  position: relative;
  width: 100px;
  float: left;
  left: -100px;
  height: 80px;
  margin-left: -100%;
  background: #0f0;
}

.right {
  position: relative;
  width: 100px;
  float: left;
  right: -100px;
  height: 80px;
  margin-left: -100px;
  background: #00f;
}

双飞翼布局

htmlCopy
	<div class="content">
		<div class="middle">
			<div class="inner-middle"></div>
		</div>
		<div class="left"></div>
		<div class="right"></div>
	</div>

cssCopy
		.content {
			overflow: hidden;
		}

		.middle {			
			width: 100%;
			float: left;
		}
               .inner-middle{
			width:100%;
			height: 80px;
			
			background: green;			
		}
		.left {
			width: 100px;
			float: left;
			height: 80px;
			margin-left: -100%;
			background: yellow;
		}

		.right {			
			width: 100px;
			float: left;
			height: 80px;
			margin-left: -100px;
			background: pink
		}