用CSS样式实现显示隐藏层

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　　此方法不用JavaScript，代码少、简单，显示的层自动在链接处

　　以下代码加入页面中，鼠标悬浮于链接“1234567890”上时，层内容“11111111”显示，鼠标离开时层恢复隐藏状态。

<a href="####" style="color:blue" onMouseOver="document.all.Layer1.style.visibility=''" onMouseOut="document.all.Layer1.style.visibility='hidden'">
1234567890</a>

<div id="Layer1" style="position:absolute; width:300px; height:100px; z-index:1; background-color: #CCFFFF; layer-background-color: #CCFFFF; border: 1px none #000000; visibility: hidden">11111111</div>

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