CSS display属性的覆盖性实例页面

CSS代码：

.displayNone { display: none; }
.displayBlock { display: block; }
                

HTML代码：

<p>
    <a href="#" class="displayNone">
        <img src="//image.zhangxinxu.com/image/study/s/s256/mm1.jpg" />
    </a>
</p>
<p>
    <a href="#" class="displayNone">
        <img class="displayBlock" src="//image.zhangxinxu.com/image/study/s/s256/mm1.jpg" />
    </a>
</p>