垂直居中：
先height再ling-height,都设成一样高
设置外边距：
margin-top,margin-left,margin-right，margin-bottom
div背景单张铺满设置：
width: 30px;
height: 30px;
line-height:
30px;
background-image:
url(../image/lzhf/one.png);
background-repeat:
no-repeat;
background-size: 100% auto;
div浮在div上：
<div style="position: relative;height:
30px;width: 100%">
<div style="height: 30px; overflow: hidden;position:
absolute;z-index: 2;width: 100%;">
<img alt="主要职责" style="width:
100%; height: 30px;"
src="../../image/ljfy/zcjgtop.png">
</div>
<div style="position: absolute;z-index:
3;margin-left:10px;height: 30px;line-height: 30px;">
<img
src="../../image/ljfy/zyzzc.png" width="30" height="30">
</div>
<div style="position: absolute;z-index:
3;margin-left: 38px;height: 30px;line-height: 30px;">
<font
style="font-weight: bold">共有内设机构20个</font>
</div>
</div>
解决非固定宽度的浮动问题：
结束加上<div style="clear:both;height: 0px;"></div>