css
<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><title>Untitled Document</title><style type="text/css"> body{ color: black; } .father{ height: 31px; background-color: grey; position: relative; } .father li{ float: left; margin-right: 5px; } .son{ display: none; background-color: red; height: 30px; top: 31px; left: 0px; } .father li:hover ul{ display: block; } .son li{ float: left; margin-right: 5px; }</style></head><body><ul class="father"> <li>first</li> <li> <a href="#">father</a> <ul class="son"> <li>son1</li> <li>son1</li> <li>son1</li> </ul> </li></ul></body></html> 初步帮楼主整理了下，IE7+和谷歌差不多，一般直接CSS样式控制的横向下拉菜单不是很好，最好是通过JS来控制，希望对楼主有所帮助。
<!DOCTYPE html><html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>横向菜单</title> <style type="text/css"> .horizontallyMenu{ padding: 10px; border: 1px solid red; } .father{ height: 31px; position: relative; list-style: none; margin: 0px; padding: 0px; } .father li{ cursor: pointer; float: left; padding: 5px; margin-right: 5px; } .father li a{ text-decoration: none; } .father li:hover ul{ display: block; } .son{ display: none; background-color: red; height: 30px; list-style: none; margin: 0px; padding: 0px; margin-top: 5px; } .son li{ cursor: pointer; padding: 5px; float: left; margin-right: 5px; } .son li:hover{ background-color: blue; } </style> </head> <body> <div class="horizontallyMenu"> <ul class="father"> <li>first</li> <li> <a href="#">father</a> <ul class="son"> <li>son1</li> <li>son1</li> <li>son1</li> </ul> </li> </ul> </div> </body></html>
