CSS 垂直居中

1. 显示方式设置成表格
   html:

   <div id="wrapper">
       <div id="cell">
           <div class="content">Content goes here.</div>
       </div>
   </div>

css:

#wrapper {
    display: table;
    height: 100px;
    background: pink;
}
#cell {
    display: table-cell;
    vertical-align: middle;
}

效果：

2. 父元素相对定位，子元素绝对定位
   html:

   <div id="wrapper">
       <div class="content">Content goes here.</div>
   </div>

css:

#wrapper {
    border: 1px solid #ccc;
    width: 600px;
    height: 400px;
    position: relative;
}
.content {
    background: pink;
    width: 300px;
    height: 200px;
    positioin: absolute;
    left: 50%;
    top: 50%;
    margin-left: -150px;
    margin-top: -100px;
}

效果：

3. CSS3 transform 代替 margin
   html:

   <div id="wrapper">
       <div class="content">Content goes here.</div>
   </div>

css:

#wrapper {
    border: 1px solid #ccc;
    width: 600px;
    height: 400px;
    position: relative;
}
.content {
    background: pink;
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
}

效果：

4. margin: auto 实现
   html:

   <div id="wrapper">
       <div class="content">Content goes here.</div>
   </div>

css:

#wrapper {
    border: 1px solid #ccc;
    width: 600px;
    height: 400px;
    position: relative;
}
.content {
    background: pink;
    width: 200px;
    height: 100px;
    position: absolute;
    left: 0;
    top: 0;
    right: 0;
    bottom: 0;
    margin: auto;
}

效果：