1. text-align: center;

1   <div class="center1">
2     <span>111</span>
3   </div>
4 
5   .center1 {
6     text-align: center;
7   }

2. margin: 0 auto;

(需要先制定一个宽度,让块级元素居中,然后让文字居中.)

1     <div class="center2">
2       <span>222</span>
3     </div>
4 
5   .center2 {
6     width: 100%;
7     margin: 0 auto;
8     text-align: center;
9   }

3. table-cell 实现几个块级元素一起居中展示.

 1     <div>
 2       <div class="center3">3111</div>
 3       <div class="center3">3222</div>
 4       <div class="center3">3333</div>
 5     </div>
 6 
 7   .center3 {
 8     display: table-cell;
 9     vertical-align: middle;
10     text-align: center;
11     width: 200px;
12     height: 200px;
13     border: 1px solid red;
14   }

4. 通过line-height和height,设置元素水平垂直居中.

 1     <div class="center4">
 2       444
 3     </div>
 4 
 5   .center4 {
 6     height: 40px;
 7     line-height: 40px;
 8     text-align: center;
 9     background-color: pink;
10   }

5. 使用CSS3 translate

　　transform: translate(-50%, -50%);

6. 使用CSS3 calc 

　　left: calc(50% - 150px);

7. 使用flex布局 (最好用)

 1     <div class="center5">
 2       555
 3     </div>
 4 
 5   .center5 {
 6     display: flex;
 7     height: 40px;
 8     align-items: center; // 水平居中
 9     justify-content: center; // 垂直居中
10     background-color: skyblue;
11   }