CSS overflow:hidden与position:absolute属性的覆盖性实例页面

CSS代码：

.overflowHidden { display: block; height: 0; overflow: hidden; }
.positionAbsolute { position: absolute; }
                

HTML代码：

<p style="height: 200px;">
    <a href="#" class="overflowHidden">
        <img src="//image.zhangxinxu.com/image/study/s/s256/mm1.jpg" />
    </a>
</p>
<p style="height: 200px;">
    <a href="#" class="overflowHidden">
        <img class="positionAbsolute" src="//image.zhangxinxu.com/image/study/s/s256/mm1.jpg" />
    </a>
</p>