编写纯 CSS 弹出菜单的原理及实现 By shawl.qiu
  摘要:
  本文介绍了使用 CSS 编写适用于 Opera, Firefox, IE 的多风格弹出菜单
  说明:
  编写 CSS 弹出菜单的要点不外乎当鼠标移到目标上时, 显示出隐藏的标签.
  要隐藏的标签使用 display:none; 属性进行隐藏.
  触发显示隐藏标签主要使用 :hover 属性, 并用 display:block; 显示隐藏的标签.
  但由于浏览器对 CSS 的支持并非一致.
  对于 Opera 或者 Firefox, 我们可以编写出纯 CSS 菜单, 他们支持任何标签的 :hover 属性.
  而对于 IE 浏览器, :hover 只对 a 标签起作用, 但我们可以使用脚本的 onmouseover, onmouseout 模拟出其他标签的 :hover 属性.
  因此编写适用于 IE 的 CSS 弹出菜单必须使用到少许的脚本.
  目录:
  1. 编写直排右侧弹出的 CSS 菜单.
  1.1 真正的基于 Opera, Firefox 纯 CSS 弹出菜单
  1.2 兼容 IE, Opera, Firefox 的 CSS 弹出菜单(脚本实现)
  2. 编写横排底部弹出的 CSS 菜单.
  2.1 真正的基于 Opera, Firefox 纯 CSS 弹出菜单
  2.2 兼容 IE, Opera, Firefox 的 CSS 弹出菜单(脚本实现)
  3. 结论
  4. 预览
  shawl.qiu
  2006-10-01
  http://blog.csdn.net/btbtd
  1. 编写直排右侧弹出的 CSS 菜单.
  1.1 真正的基于 Opera, Firefox 纯 CSS 弹出菜单
   
linenum 
- <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 
 - " http://www.w3.org/TR/html4/loose.dtd"> 
 - <html> 
 - <head> 
 - <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 
 - <title>Untitled Document</title> 
 - <style type="text/css"> 
 - /*<![CDATA[*/ /* shawl.qiu pure css popup menu demo */ 
 -     body{ margin:0px auto; width:768px; /* 定义页面居中显示,*/} 
 -     *{text-decoration:none!important; /* 定义所有链接不显示下划线 */} 
 -     .pmVerticalRightOut{background-color:#fff!important; /* 定义主菜单域背景色 */}  
 -     .pmVerticalRightOut .level{  /* 定义一级类别属性 */ 
 -         width:120px; /* 宽度 */ 
 -         height:17; /* 高度 */ 
 -         position:relative; /* 显示位置为相对位置 */ 
 -         display:block; /* 以块模式显示 */ 
 -         background-color:#D8D8D8; /* 背景色 */ 
 -         padding:0px 2px; /* 文字内补丁间隔 */ 
 -         margin:0px 0px 1px 0px; /* 菜单外补丁间隔 */ 
 -     } 
 -     .pmVerticalRightOut .level:hover { /* 当鼠标划过一级菜单时 */ 
 -         background-color:#6633FF; /* 背景色 */ 
 -         color:#FFFFFF; /* 文字颜色 */ 
 -     } 
 -     .pmVerticalRightOut .level_{display:none; /* 默认隐藏二级类别 */} 
 -      
 -     .pmVerticalRightOut .level:hover .level_ { /* 鼠标划过时触发显示二级类别 */ 
 -         display:block; /* 以块显示 */ 
 -         left:124px; /* 相对于一级类别显示的位置 */ 
 -         width:120px; /* 宽度 */ 
 -         height:auto; /* 高度 */ 
 -         top:0px; /* 相对于一级类别所在位置的顶端 */ 
 -         background-color:#EFEFEF; /* 定义背景色 */ 
 -         position:absolute; /* 位置为绝对位置 */ 
 -     } 
 -     .pmVerticalRightOut .level:hover .level_ .level_title { 
 -         /* 定义二级类别标题样式 */ 
 -         font-weight:bold; /* 字体加粗 */ 
 -         background-color:#A7ADFE; /* 背景色 */ 
 -         color:white; /* 文字颜色 */ 
 -     } 
 -     .pmVerticalRightOut .level:hover .level_ a:hover { 
 -         /* 定义二级类别链接显示样式 */ 
 -         background-color:#F83658; /* 背景色 */ 
 -         color:white; /* 文字颜色 */ 
 -     } 
 -     .pmVerticalRightOut .level_ * {  
 -         /* 定义所有二级类别通用属性 */ 
 -         display:block; /* 以块显示 */ 
 -         color:black; /* 文字颜色 */ 
 -         padding:0px 2px; /* 内补丁间隔 */ 
 -     } 
 - /*]]>*/ 
 - </style> 
 - </head> 
 - <body> 
 - <p/><p/><p/><p/><p/> 
 - <div class="pmVerticalRightOut" id="pmVerticalRightOut"> 
 -     <div class="level"> 
 -         <div class="levelTitle">level</div> 
 -         <div class="level_"> 
 -             <div class="level_title">level_ title</div> 
 -             <a href="?cat=level&id=1">level_ title 1</a> 
 -             <a href="?cat=level&id=2">level_ title 2</a> 
 -             <a href="?cat=level&id=3">level_ title 3</a> 
 -             <a href="?cat=level&id=4">level_ title 4</a> 
 -             <a href="?cat=level&id=5">level_ title 5</a> 
 -         </div> 
 -     </div> 
 -     <div class="level"> 
 -         <div class="levelTitle">level 1</div> 
 -         <div class="level_"> 
 -             <div class="level_title">level_ title</div> 
 -             <a href="?cat=level_1&id=1">level_ title 1</a> 
 -             <a href="?cat=level_1&id=2">level_ title 2</a> 
 -             <a href="?cat=level_1&id=3">level_ title 3</a> 
 -             <a href="?cat=level_1&id=4">level_ title 4</a> 
 -             <a href="?cat=level_1&id=5">level_ title 5</a> 
 -         </div> 
 -     </div> 
 -     <div class="level"> 
 -         <div class="levelTitle">level 2</div> 
 -         <div class="level_"> 
 -             <div class="level_title">level_ title</div> 
 -             <a href="?cat=level_2&id=1">level_ title 1</a> 
 -             <a href="?cat=level_2&id=2">level_ title 2</a> 
 -             <a href="?cat=level_2&id=3">level_ title 3</a> 
 -             <a href="?cat=level_2&id=4">level_ title 4</a> 
 -             <a href="?cat=level_2&id=5">level_ title 5</a> 
 -         </div> 
 -     </div> 
 -     <div class="level"> 
 -         <div class="levelTitle">level 3</div> 
 -         <div class="level_"> 
 -             <div class="level_title">level_ title</div> 
 -             <a href="?cat=level_3&id=1">level_ title 1</a> 
 -             <a href="?cat=level_3&id=2">level_ title 2</a> 
 -             <a href="?cat=level_3&id=3">level_ title 3</a> 
 -             <a href="?cat=level_3&id=4">level_ title 4</a> 
 -             <a href="?cat=level_3&id=5">level_ title 5</a> 
 -         </div> 
 -     </div> 
 -     <div class="level"> 
 -         <div class="levelTitle">level 4</div> 
 -         <div class="level_"> 
 -             <div class="level_title">level_ title</div> 
 -             <a href="?cat=level_4&id=1">level_ title 1</a> 
 -             <a href="?cat=level_4&id=2">level_ title 2</a> 
 -             <a href="?cat=level_4&id=3">level_ title 3</a> 
 -             <a href="?cat=level_4&id=4">level_ title 4</a> 
 -             <a href="?cat=level_4&id=5">level_ title 5</a> 
 -         </div> 
 -     </div> 
 - </div> 
 - </body> 
 - </html> 
 
  1.2 兼容 IE, Opera, Firefox 的 CSS 弹出菜单(脚本实现)
   
linenum 
- <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 
 - " http://www.w3.org/TR/html4/loose.dtd"> 
 - <html> 
 - <head> 
 - <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 
 - <title>Untitled Document</title> 
 - <style type="text/css"> 
 - /*<![CDATA[*/ /* shawl.qiu pure css popup menu demo */ 
 -     body{ margin:0px auto; width:768px; /* 定义页面居中显示,*/} 
 -     *{text-decoration:none!important; /* 定义所有链接不显示下划线 */} 
 -     /* ------------------- start 针对 Opera, Firefox 的 CSS 弹出菜单 -------------------*/ 
 -     .pmVerticalRightOut{background-color:#fff!important; /* 定义主菜单域背景色 */}  
 -     .pmVerticalRightOut .level{  /* 定义一级类别属性 */ 
 -         width:120px; /* 宽度 */ 
 -         height:17; /* 高度 */ 
 -         position:relative; /* 显示位置为相对位置 */ 
 -         display:block; /* 以块模式显示 */ 
 -         background-color:#D8D8D8; /* 背景色 */ 
 -         padding:0px 2px; /* 文字内补丁间隔 */ 
 -         margin:0px 0px 1px 0px; /* 菜单外补丁间隔 */ 
 -     } 
 -     .pmVerticalRightOut .level:hover { /* 当鼠标划过一级菜单时 */ 
 -         background-color:#6633FF; /* 背景色 */ 
 -         color:#FFFFFF; /* 文字颜色 */ 
 -     } 
 -     .pmVerticalRightOut .level_{display:none; /* 默认隐藏二级类别 */} 
 -      
 -     .pmVerticalRightOut .level:hover .level_ { /* 鼠标划过时触发显示二级类别 */ 
 -         display:block; /* 以块显示 */ 
 -         left:124px; /* 相对于一级类别显示的位置 */ 
 -         width:120px; /* 宽度 */ 
 -         height:auto; /* 高度 */ 
 -         top:0px; /* 相对于一级类别所在位置的顶端 */ 
 -         background-color:#EFEFEF; /* 定义背景色 */ 
 -         position:absolute; /* 位置为绝对位置 */ 
 -     } 
 -     .pmVerticalRightOut .level:hover .level_ .level_title { 
 -         /* 定义二级类别标题样式 */ 
 -         font-weight:bold; /* 字体加粗 */ 
 -         background-color:#A7ADFE; /* 背景色 */ 
 -         color:white; /* 文字颜色 */ 
 -     } 
 -     .pmVerticalRightOut .level:hover .level_ a:hover { 
 -         /* 定义二级类别链接显示样式 */ 
 -         background-color:#F83658; /* 背景色 */ 
 -         color:white; /* 文字颜色 */ 
 -     } 
 -     .pmVerticalRightOut .level:hover .level_ * {  
 -         /* 定义所有二级类别通用属性 */ 
 -         display:block; /* 以块显示 */ 
 -         color:black; /* 文字颜色 */ 
 -         padding:0px 2px; /* 内补丁间隔 */ 
 -     } 
 -     /* ------------------- end 针对 Opera, Firefox 的 CSS 弹出菜单 -------------------*/ 
 -      
 -     /* ------------------- start 针对 IE 的 CSS 弹出菜单 -------------------*/ 
 -     .levelIe{  /* 定义一级类别属性 */ 
 -         width:120px; /* 宽度 */ 
 -         height:17; /* 高度 */ 
 -         position:relative; /* 显示位置为相对位置 */ 
 -         display:block; /* 以块模式显示 */ 
 -         background-color:#D8D8D8; /* 背景色 */ 
 -         padding:0px 2px; /* 文字内补丁间隔 */ 
 -         margin:0px 0px 1px 0px; /* 菜单外补丁间隔 */ 
 -     } 
 -     .levelIe .level_ { /* 鼠标划过时触发显示二级类别 */ 
 -         display:block; /* 以块显示 */ 
 -         left:124px; /* 相对于一级类别显示的位置 */ 
 -         width:120px; /* 宽度 */ 
 -         height:auto; /* 高度 */ 
 -         top:0px; /* 相对于一级类别所在位置的顶端 */ 
 -         background-color:#EFEFEF; /* 定义背景色 */ 
 -         position:absolute; /* 位置为绝对位置 */ 
 -     } 
 -     .levelIe .level_ .level_title { 
 -         /* 定义二级类别标题样式 */ 
 -         font-weight:bold; /* 字体加粗 */ 
 -         background-color:#A7ADFE; /* 背景色 */ 
 -         color:white; /* 文字颜色 */ 
 -     } 
 -     .levelIe .level_ a:hover { 
 -         /* 定义二级类别链接显示样式 */ 
 -         background-color:#F83658; /* 背景色 */ 
 -         color:white; /* 文字颜色 */ 
 -     } 
 -     .levelIe .level_ * {  
 -         /* 定义所有二级类别通用属性 */ 
 -         display:block; /* 以块显示 */ 
 -         color:black; /* 文字颜色 */ 
 -         padding:0px 2px; /* 内补丁间隔 */ 
 -     } 
 -     /* ------------------- end 针对 IE 的 CSS 弹出菜单 -------------------*/ 
 - /*]]>*/ 
 - </style> 
 - <script type="text/javascript"> 
 - //<![CDATA[ 
 - if (navigator.appName=="Microsoft Internet Explorer") { 
 -     function fPmVerticalRightOut() { 
 -         var getItem = document.getElementById("pmVerticalRightOut").getElementsByTagName("div"); 
 -         for (var i=0; i<getItem.length; i++) { 
 -             getItem[i].onmouseover=function() {  
 -                 if(    this.className=="level"){ 
 -                     this.className="levelIe"; 
 -                 } 
 -             } 
 -             getItem[i].onmouseout=function() {  
 -                 if(    this.className=="levelIe"){ 
 -                     this.className="level"; 
 -                 } 
 -             }//css popup menu script by shawl.qiu 
 -         } 
 -     } 
 -     window.onload=fPmVerticalRightOut; 
 - } 
 - //]]> 
 - </script> 
 - </head> 
 - <body> 
 - <p/><p/><p/><p/><p/> 
 - <div class="pmVerticalRightOut" id="pmVerticalRightOut"> 
 -     <div class="level"> 
 -         <div class="levelTitle">level</div> 
 -         <div class="level_"> 
 -             <div class="level_title">level_ title</div> 
 -             <a href="?cat=level&id=1">level_ title 1</a> 
 -             <a href="?cat=level&id=2">level_ title 2</a> 
 -             <a href="?cat=level&id=3">level_ title 3</a> 
 -             <a href="?cat=level&id=4">level_ title 4</a> 
 -             <a href="?cat=level&id=5">level_ title 5</a> 
 -         </div> 
 -     </div> 
 -     <div class="level"> 
 -         <div class="levelTitle">level 1</div> 
 -         <div class="level_"> 
 -             <div class="level_title">level_ title</div> 
 -             <a href="?cat=level_1&id=1">level_ title 1</a> 
 -             <a href="?cat=level_1&id=2">level_ title 2</a> 
 -             <a href="?cat=level_1&id=3">level_ title 3</a> 
 -             <a href="?cat=level_1&id=4">level_ title 4</a> 
 -             <a href="?cat=level_1&id=5">level_ title 5</a> 
 -         </div> 
 -     </div> 
 -     <div class="level"> 
 -         <div class="levelTitle">level 2</div> 
 -         <div class="level_"> 
 -             <div class="level_title">level_ title</div> 
 -             <a href="?cat=level_2&id=1">level_ title 1</a> 
 -             <a href="?cat=level_2&id=2">level_ title 2</a> 
 -             <a href="?cat=level_2&id=3">level_ title 3</a> 
 -             <a href="?cat=level_2&id=4">level_ title 4</a> 
 -             <a href="?cat=level_2&id=5">level_ title 5</a> 
 -         </div> 
 -     </div> 
 -     <div class="level"> 
 -         <div class="levelTitle">level 3</div> 
 -         <div class="level_"> 
 -             <div class="level_title">level_ title</div> 
 -             <a href="?cat=level_3&id=1">level_ title 1</a> 
 -             <a href="?cat=level_3&id=2">level_ title 2</a> 
 -             <a href="?cat=level_3&id=3">level_ title 3</a> 
 -             <a href="?cat=level_3&id=4">level_ title 4</a> 
 -             <a href="?cat=level_3&id=5">level_ title 5</a> 
 -         </div> 
 -     </div> 
 -     <div class="level"> 
 -         <div class="levelTitle">level 4</div> 
 -         <div class="level_"> 
 -             <div class="level_title">level_ title</div> 
 -             <a href="?cat=level_4&id=1">level_ title 1</a> 
 -             <a href="?cat=level_4&id=2">level_ title 2</a> 
 -             <a href="?cat=level_4&id=3">level_ title 3</a> 
 -             <a href="?cat=level_4&id=4">level_ title 4</a> 
 -             <a href="?cat=level_4&id=5">level_ title 5</a> 
 -         </div> 
 -     </div> 
 - </div> 
 - </body> 
 - </html> 
 
  2. 编写横排底部弹出的 CSS 菜单.
  2.1 真正的基于 Opera, Firefox 纯 CSS 弹出菜单
   
linenum 
- <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 
 - " http://www.w3.org/TR/html4/loose.dtd"> 
 - <html> 
 - <head> 
 - <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 
 - <title>Untitled Document</title> 
 - <style type="text/css"> 
 - /*<![CDATA[*/ /* shawl.qiu pure css popup menu demo */ 
 -     body{ margin:0px auto; width:768px; /* 定义页面居中显示,*/} 
 -     *{text-decoration:none!important; /* 定义所有链接不显示下划线 */} 
 -     .pmHorizontalBottomOut{background-color:#fff!important; /* 定义主菜单域背景色 */}  
 -     .pmHorizontalBottomOut .level{  /* 定义一级类别属性 */ 
 -         width:120px; /* 宽度 */ 
 -         height:17; /* 高度 */ 
 -         position:relative; /* 显示位置为相对位置 */ 
 -         display:block; /* 以块模式显示 */ 
 -         background-color:#D8D8D8; /* 背景色 */ 
 -         padding:0px 2px; /* 文字内补丁间隔 */ 
 -         margin:0px 1px 0px 0px; /* 菜单外补丁间隔 */ 
 -         float:left; 
 -     } 
 -     .pmHorizontalBottomOut .level:hover { /* 当鼠标划过一级菜单时 */ 
 -         background-color:#6633FF; /* 背景色 */ 
 -         color:#FFFFFF; /* 文字颜色 */ 
 -     } 
 -     .pmHorizontalBottomOut .level_{display:none; /* 默认隐藏二级类别 */} 
 -      
 -     .pmHorizontalBottomOut .level:hover .level_ { /* 鼠标划过时触发显示二级类别 */ 
 -         display:block; /* 以块显示 */ 
 -         width:124px; /* 宽度 */ 
 -         height:auto; /* 高度 */ 
 -         margin:0px -2px 0px -2px; /* 外补丁 */ 
 -         background-color:#EFEFEF; /* 定义背景色 */ 
 -         position:absolute; /* 位置为绝对位置 */ 
 -     } 
 -     .pmHorizontalBottomOut .level:hover .level_ .level_title { 
 -         /* 定义二级类别标题样式 */ 
 -         font-weight:bold; /* 字体加粗 */ 
 -         background-color:#A7ADFE; /* 背景色 */ 
 -         color:white; /* 文字颜色 */ 
 -     } 
 -     .pmHorizontalBottomOut .level:hover .level_ a:hover { 
 -         /* 定义二级类别链接显示样式 */ 
 -         background-color:#F83658; /* 背景色 */ 
 -         color:white; /* 文字颜色 */ 
 -     } 
 -     .pmHorizontalBottomOut .level_ * {  
 -         /* 定义所有二级类别通用属性 */ 
 -         display:block; /* 以块显示 */ 
 -         color:black; /* 文字颜色 */ 
 -         padding:0px 2px; /* 内补丁间隔 */ 
 -     } 
 - /*]]>*/ 
 - </style> 
 - </head> 
 - <body> 
 - <p/><p/><p/><p/><p/> 
 - <div class="pmHorizontalBottomOut" id="pmHorizontalBottomOut"> 
 -     <div class="level"> 
 -         <div class="levelTitle">level</div> 
 -         <div class="level_"> 
 -             <div class="level_title">level_ title</div> 
 -             <a href="?cat=level&id=1">level_ title 1</a> 
 -             <a href="?cat=level&id=2">level_ title 2</a> 
 -             <a href="?cat=level&id=3">level_ title 3</a> 
 -             <a href="?cat=level&id=4">level_ title 4</a> 
 -             <a href="?cat=level&id=5">level_ title 5</a> 
 -         </div> 
 -     </div> 
 -     <div class="level"> 
 -         <div class="levelTitle">level 1</div> 
 -         <div class="level_"> 
 -             <div class="level_title">level_ title</div> 
 -             <a href="?cat=level_1&id=1">level_ title 1</a> 
 -             <a href="?cat=level_1&id=2">level_ title 2</a> 
 -             <a href="?cat=level_1&id=3">level_ title 3</a> 
 -             <a href="?cat=level_1&id=4">level_ title 4</a> 
 -             <a href="?cat=level_1&id=5">level_ title 5</a> 
 -         </div> 
 -     </div> 
 -     <div class="level"> 
 -         <div class="levelTitle">level 2</div> 
 -         <div class="level_"> 
 -             <div class="level_title">level_ title</div> 
 -             <a href="?cat=level_2&id=1">level_ title 1</a> 
 -             <a href="?cat=level_2&id=2">level_ title 2</a> 
 -             <a href="?cat=level_2&id=3">level_ title 3</a> 
 -             <a href="?cat=level_2&id=4">level_ title 4</a> 
 -             <a href="?cat=level_2&id=5">level_ title 5</a> 
 -         </div> 
 -     </div> 
 -     <div class="level"> 
 -         <div class="levelTitle">level 3</div> 
 -         <div class="level_"> 
 -             <div class="level_title">level_ title</div> 
 -             <a href="?cat=level_3&id=1">level_ title 1</a> 
 -             <a href="?cat=level_3&id=2">level_ title 2</a> 
 -             <a href="?cat=level_3&id=3">level_ title 3</a> 
 -             <a href="?cat=level_3&id=4">level_ title 4</a> 
 -             <a href="?cat=level_3&id=5">level_ title 5</a> 
 -         </div> 
 -     </div> 
 -     <div class="level"> 
 -         <div class="levelTitle">level 4</div> 
 -         <div class="level_"> 
 -             <div class="level_title">level_ title</div> 
 -             <a href="?cat=level_4&id=1">level_ title 1</a> 
 -             <a href="?cat=level_4&id=2">level_ title 2</a> 
 -             <a href="?cat=level_4&id=3">level_ title 3</a> 
 -             <a href="?cat=level_4&id=4">level_ title 4</a> 
 -             <a href="?cat=level_4&id=5">level_ title 5</a> 
 -         </div> 
 -     </div> 
 - </div> 
 - </body> 
 - </html> 
 
  2.2 兼容 IE, Opera, Firefox 的 CSS 弹出菜单(脚本实现)
   
linenum 
- <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 
 - " http://www.w3.org/TR/html4/loose.dtd"> 
 - <html> 
 - <head> 
 - <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 
 - <title>Untitled Document</title> 
 - <style type="text/css"> 
 - /*<![CDATA[*/ /* shawl.qiu pure css popup menu demo */ 
 -     body{ margin:0px auto; width:768px; /* 定义页面居中显示,*/} 
 -     *{text-decoration:none!important; /* 定义所有链接不显示下划线 */} 
 -     /* ------------------- start 针对 Opera, Firefox 的 CSS 弹出菜单 -------------------*/ 
 -     .pmHorizontalBottomOut{background-color:#fff!important; /* 定义主菜单域背景色 */}  
 -     .pmHorizontalBottomOut .level{  /* 定义一级类别属性 */ 
 -         width:120px; /* 宽度 */ 
 -         height:17; /* 高度 */ 
 -         position:relative; /* 显示位置为相对位置 */ 
 -         display:block; /* 以块模式显示 */ 
 -         background-color:#D8D8D8; /* 背景色 */ 
 -         padding:0px 2px; /* 文字内补丁间隔 */ 
 -         margin:0px 1px 0px 0px; /* 菜单外补丁间隔 */ 
 -         float:left; 
 -     } 
 -     .pmHorizontalBottomOut .level:hover { /* 当鼠标划过一级菜单时 */ 
 -         background-color:#6633FF; /* 背景色 */ 
 -         color:#FFFFFF; /* 文字颜色 */ 
 -     } 
 -     .pmHorizontalBottomOut .level_{display:none; /* 默认隐藏二级类别 */} 
 -      
 -     .pmHorizontalBottomOut .level:hover .level_ { /* 鼠标划过时触发显示二级类别 */ 
 -         display:block; /* 以块显示 */ 
 -         width:124px; /* 宽度 */ 
 -         height:auto; /* 高度 */ 
 -         margin:0px -2px 0px -2px; /* 外补丁 */ 
 -         background-color:#EFEFEF; /* 定义背景色 */ 
 -         position:absolute; /* 位置为绝对位置 */ 
 -     } 
 -     .pmHorizontalBottomOut .level:hover .level_ .level_title { 
 -         /* 定义二级类别标题样式 */ 
 -         font-weight:bold; /* 字体加粗 */ 
 -         background-color:#A7ADFE; /* 背景色 */ 
 -         color:white; /* 文字颜色 */ 
 -     } 
 -     .pmHorizontalBottomOut .level:hover .level_ a:hover { 
 -         /* 定义二级类别链接显示样式 */ 
 -         background-color:#F83658; /* 背景色 */ 
 -         color:white; /* 文字颜色 */ 
 -     } 
 -     .pmHorizontalBottomOut .level_ * {  
 -         /* 定义所有二级类别通用属性 */ 
 -         display:block; /* 以块显示 */ 
 -         color:black; /* 文字颜色 */ 
 -         padding:0px 2px; /* 内补丁间隔 */ 
 -     } 
 -     /* ------------------- end 针对 Opera, Firefox 的 CSS 弹出菜单 -------------------*/ 
 -      
 -     /* ------------------- start 针对 IE 的 CSS 弹出菜单 -------------------*/ 
 -     .levelIe{  /* 定义一级类别属性 */ 
 -         width:120px; /* 宽度 */ 
 -         height:17; /* 高度 */ 
 -         position:relative; /* 显示位置为相对位置 */ 
 -         display:block; /* 以块模式显示 */ 
 -         background-color:#D8D8D8; /* 背景色 */ 
 -         padding:0px 2px; /* 文字内补丁间隔 */ 
 -         margin:0px 1px 0px 0px; /* 菜单外补丁间隔 */ 
 -         float:left; 
 -     } 
 -     .levelIe { /* 当鼠标划过一级菜单时 */ 
 -         background-color:#6633FF; /* 背景色 */ 
 -         color:#FFFFFF; /* 文字颜色 */ 
 -     } 
 -     .levelIe .level_ { /* 鼠标划过时触发显示二级类别 */ 
 -         display:block; /* 以块显示 */ 
 -         width:124px; /* 宽度 */ 
 -         height:auto; /* 高度 */ 
 -         margin:0px -2px 0px -2px; /* 外补丁 */ 
 -         background-color:#EFEFEF; /* 定义背景色 */ 
 -         position:absolute; /* 位置为绝对位置 */ 
 -     } 
 -     .levelIe .level_ .level_title { 
 -         /* 定义二级类别标题样式 */ 
 -         font-weight:bold; /* 字体加粗 */ 
 -         background-color:#A7ADFE; /* 背景色 */ 
 -         color:white; /* 文字颜色 */ 
 -     } 
 -     .levelIe .level_ a:hover { 
 -         /* 定义二级类别链接显示样式 */ 
 -         background-color:#F83658; /* 背景色 */ 
 -         color:white; /* 文字颜色 */ 
 -     } 
 -     .levelIe .level_ * {  
 -         /* 定义所有二级类别通用属性 */ 
 -         display:block; /* 以块显示 */ 
 -         color:black; /* 文字颜色 */ 
 -         padding:0px 2px; /* 内补丁间隔 */ 
 -     } 
 -     /* ------------------- end 针对 IE 的 CSS 弹出菜单 -------------------*/ 
 - /*]]>*/ 
 - </style> 
 - <script type="text/javascript"> 
 - //<![CDATA[ 
 - if (navigator.appName=="Microsoft Internet Explorer") { 
 -     function fPmHorizontalBottomOut() { 
 -         var getItem = document.getElementById("pmHorizontalBottomOut").getElementsByTagName("div"); 
 -         for (var i=0; i<getItem.length; i++) { 
 -             getItem[i].onmouseover=function() {  
 -                 if(    this.className=="level"){ 
 -                     this.className="levelIe"; 
 -                 } 
 -             } 
 -             getItem[i].onmouseout=function() {  
 -                 if(    this.className=="levelIe"){ 
 -                     this.className="level"; 
 -                 } 
 -             }//css popup menu script by shawl.qiu 
 -         } 
 -     } 
 -     window.onload=fPmHorizontalBottomOut; 
 - } 
 - //]]> 
 - </script> 
 - </head> 
 - <body> 
 - <p/><p/><p/><p/><p/> 
 - <div class="pmHorizontalBottomOut" id="pmHorizontalBottomOut"> 
 -     <div class="level"> 
 -         <div class="levelTitle">level</div> 
 -         <div class="level_"> 
 -             <div class="level_title">level_ title</div> 
 -             <a href="?cat=level&id=1">level_ title 1</a> 
 -             <a href="?cat=level&id=2">level_ title 2</a> 
 -             <a href="?cat=level&id=3">level_ title 3</a> 
 -             <a href="?cat=level&id=4">level_ title 4</a> 
 -             <a href="?cat=level&id=5">level_ title 5</a> 
 -         </div> 
 -     </div> 
 -     <div class="level"> 
 -         <div class="levelTitle">level 1</div> 
 -         <div class="level_"> 
 -             <div class="level_title">level_ title</div> 
 -             <a href="?cat=level_1&id=1">level_ title 1</a> 
 -             <a href="?cat=level_1&id=2">level_ title 2</a> 
 -             <a href="?cat=level_1&id=3">level_ title 3</a> 
 -             <a href="?cat=level_1&id=4">level_ title 4</a> 
 -             <a href="?cat=level_1&id=5">level_ title 5</a> 
 -         </div> 
 -     </div> 
 -     <div class="level"> 
 -         <div class="levelTitle">level 2</div> 
 -         <div class="level_"> 
 -             <div class="level_title">level_ title</div> 
 -             <a href="?cat=level_2&id=1">level_ title 1</a> 
 -             <a href="?cat=level_2&id=2">level_ title 2</a> 
 -             <a href="?cat=level_2&id=3">level_ title 3</a> 
 -             <a href="?cat=level_2&id=4">level_ title 4</a> 
 -             <a href="?cat=level_2&id=5">level_ title 5</a> 
 -         </div> 
 -     </div> 
 -     <div class="level"> 
 -         <div class="levelTitle">level 3</div> 
 -         <div class="level_"> 
 -             <div class="level_title">level_ title</div> 
 -             <a href="?cat=level_3&id=1">level_ title 1</a> 
 -             <a href="?cat=level_3&id=2">level_ title 2</a> 
 -             <a href="?cat=level_3&id=3">level_ title 3</a> 
 -             <a href="?cat=level_3&id=4">level_ title 4</a> 
 -             <a href="?cat=level_3&id=5">level_ title 5</a> 
 -         </div> 
 -     </div> 
 -     <div class="level"> 
 -         <div class="levelTitle">level 4</div> 
 -         <div class="level_"> 
 -             <div class="level_title">level_ title</div> 
 -             <a href="?cat=level_4&id=1">level_ title 1</a> 
 -             <a href="?cat=level_4&id=2">level_ title 2</a> 
 -             <a href="?cat=level_4&id=3">level_ title 3</a> 
 -             <a href="?cat=level_4&id=4">level_ title 4</a> 
 -             <a href="?cat=level_4&id=5">level_ title 5</a> 
 -         </div> 
 -     </div> 
 - </div> 
 - </body> 
 - </html> 
 
  3. 结论
  以上例子可以看出, 如果已经编写出一个可用的CSS弹出菜单例子, 那要编写出弹出位置在其他地方的 CSS 弹出菜单的话, 只须小小修改一下就 OK.
  4. 预览
  4.1 1.2 兼容 IE, Opera, Firefox 的 CSS 弹出菜单(脚本实现) 的预览
   
- 
 
  4.2 2.2 兼容 IE, Opera, Firefox 的 CSS 弹出菜单(脚本实现) 的预览
   
-