我有一个带有背景图像的div容器和背景图像上的两个图标。问题是当我将鼠标指向图标时，它不允许点击图像并打开超链接。这是我得到的代码：
<style type="text/css">
.containerdiv { float: left; position: relative; left: -10px; top: -10px;}
.cornerimage1 { position: absolute; top: 75%; left: 0.5%;}
.cornerimage2 { position: absolute; bottom: 23%; left: 0.5%;}
</style>
<div class="containerdiv">
<iframe src="images/mybackground.jpg" width="550" height="314" frameborder="0" scrolling="no"></iframe>
<a href="//facebook.com" target="_blank" rel="alternate"><img class="cornerimage1" src="images/iconfacebook.png" alt="" width="90" height="34"></a>
<a href="//twitter.com" target="_blank" rel="alternate"><img class="cornerimage2" src="images/icontwitter.png" alt="" width="90" height="34"></a>
</div>