div背景透明样式：
样式代码：
.alert{filter:alpha(opacity=100); /* IE */ -moz-opacity:1.0; /* Moz + FF */
opacity: 1.0; height:300px; 500px; background:#ccc; left:50%; top:50%;margin-top:-150px;margin-left:-250px;position:absolute;z-index:99; text-align:center; padding:20px;}
使用方法：
<div class=”alert”>
背景透明
</div>
html代码：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http- equiv="Content-Type" content="text/html; charset=utf-8" /> <title>100素材网</title> <style type="text/css"> .alert {filter:alpha(opacity=100); /* IE */ -moz-opacity:1.0; /* Moz + FF */ opacity: 1.0; height:300px; 500px; background:#ccc; left:50%; top:50%;margin-top:-150px;margin-left: -250px;position:absolute;z-index:99; text-align:center; padding:20px} </style> </head> <body> <div class="alert">100素材网</div> </body> </html>