DIV+CSS+JS 实现居中浮动层对话框

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3c.org/TR/1999/REC-html401-19991224/loose.dtd"> <HTML xml:lang="zn" xmlns="http://www.w3.org/1999/xhtml"> <HEAD> <TITLE>浮动层居中的对话框效果演示</TITLE> <FCK:META http-equiv=content-type content="application/xhtml+xml; charset=gb2312" /> <STYLE type=text/css> HTML { HEIGHT: 100% } BODY { HEIGHT: 100% } BODY { FONT-SIZE: 14px; FONT-FAMILY: Tahoma, Verdana, sans-serif } DIV.neat-dialog-cont { Z-INDEX: 98; BACKGROUND: none transparent scroll repeat 0% 0%; LEFT: 0px; WIDTH: 100%; POSITION: absolute; TOP: 0px; HEIGHT: 100% } DIV.neat-dialog-bg { Z-INDEX: -1; FILTER: alpha(opacity=70); LEFT: 0px; WIDTH: 100%; POSITION: absolute; TOP: 0px; HEIGHT: 100%; BACKGROUND-COLOR: #eee; opacity: 0.7 } DIV.neat-dialog { BORDER-RIGHT: #555 1px solid; BORDER-TOP: #555 1px solid; Z-INDEX: 99; MARGIN-LEFT: auto; BORDER-LEFT: #555 1px solid; WIDTH: 30%; MARGIN-RIGHT: auto; BORDER-BOTTOM: #555 1px solid; POSITION: relative; TOP: 25%; BACKGROUND-COLOR: #fff } DIV.neat-dialog-title { PADDING-RIGHT: 0.3em; PADDING-LEFT: 0.3em; FONT-SIZE: 0.8em; PADDING-BOTTOM: 0.1em; MARGIN: 0px; LINE-HEIGHT: 1.2em; PADDING-TOP: 0.1em; BORDER-BOTTOM: #444 1px solid; POSITION: relative } IMG.nd-cancel { RIGHT: 0.2em; POSITION: absolute; TOP: 0.2em } DIV.neat-dialog P { PADDING-RIGHT: 0.2em; PADDING-LEFT: 0.2em; PADDING-BOTTOM: 0.2em; PADDING-TOP: 0.2em; TEXT-ALIGN: center } </STYLE>  <BODY> <H1>浮动层居中的效果</H1> <BUTTON onclick=openDialog()>点此演示效果</BUTTON> </BODY></HTML> 

[Ctrl+A 全选 注:引入外部Js需再刷新一下页面才能执行]