***最灵活的方式

我的 demo on dabblet.com

The best and most flexible way

My demo on dabblet.com

这个演示的主要技巧是在正常的元素流从上到下，所以 margin-top：auto 设置为零。然而，绝对定位的元素对于分配***空间是相同的，并且类似地可以在指定的 top 和底部（在IE7中不起作用）。

The main trick in this demo is that in the normal flow of elements going from top to bottom, so the margin-top: auto is set to zero. However, an absolutely positioned element acts the same for distribution of free space, and similarly can be centered vertically at the specified top and bottom (does not work in IE7).

<div></div>

CSS：

CSS:

div {
    width: 100px;
    height: 100px;
    background-color: red;

    position: absolute;
    top:0;
    bottom: 0;
    left: 0;
    right: 0;

    margin: auto;
}