两栏布局自适应主流方法

<div class='container'>
<div class='left'>1</div>
<div class='right'>2</div>
</div>

//1: absolute + padding + %
.container{padding-left: 200px; position: relative;}
.left{height: 200px; position: absolute; left: 0;}
.right{width: 100%;}    //block元素, width可不设

//2: float + BFC
.left{float: left; width: 200px;}
.right{overflow: hidden;}

//3: flex
.container{display: flex;}
.left{width: 200px;}
.right{flex: 1;}