左右自适应的div是如何弄的啊，我不大明白

Question

左右自适应的div是如何弄的啊，我不大明白

Answer 1

自适应的div一般都是以百分比来设置宽与高.

Answer 2

#mainbg{
               width:789px;
               background:#FF9999;
               padding:0; 
             }
#right{
            float:right; /*使其浮动在container的右边*/
            width:637px;      
            margin:2px 0px 2px 0px;
            padding:0;  
            background:#99CCFF;
            text-align:left;
        }
#left{
          float:left;/*使其浮动在right层的左边*/
          width:150px;
          margin:2px 2px 0px 0px;
          padding:0;
          background:#CC99FF;
          text-align:left;    
<div id="mainbg"></div>
<div id="right">Right<p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p></div>
<div id="left">Left<p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p><p>1</p></div>
</div>

Answer 3

支持楼上的，用
float:right
float:left
来定义