1,Div水平居中：
<div style="margin:0px auto;width:100px;height:100px;background:#FF0000;">
2，div水平排列
<div style="float:left; width:20%; height:100px; background:#FF0000;"></div> <div style="float:left; width:60%; height:200px; background:#000000;"></div> <div style="float:left; width:20%; height:100px; background:#FF0000;"></div>
3,