css 元素居中方法

 1 <div class="nav-content">
 2                 <ul ng-click="navItem($event)" ng-model="navType">
 3                     <li id="nav_msglist">
 4                         <a href="#/">消息列表</a>
 5                     </li>
 6                     <li id="mislist">
 7                         <a href="#/">通知列表</a>
 8                     </li>
 9                     <li>
10                         <a href="#/">消息列表</a>
11                     </li>
12                     <li>
13                         <a href="#/">消息列表</a>
14                     </li>
15                     <li id="userset">
16                         <a href="#/userset">账号设置</a>
17                     </li>
18                 </ul>
19             </div>

1 .nav-content li a{color: #6f6f6f;position: absolute;-webkit-transform: translateY(-50%);top: 50%;display: block;}

1 <div class="msg-operation">
2       <div class="optico"><img src="images/collect-ico.png" /></div>
3        <div class="optico"><img src="images/collect-ico.png" /></div>
4        <div clas="optico"><img src="images/collect-ico.png" /></div>
5  </div>

1 .optico{ width: 30%;display: inline-block;position: relative;text-align: right;}
2 .optico img{height: 20px;width: 20px;position: absolute;top: 50%;margin-top: -10px;left: 50%;margin-left: 10px;}