Below is the CSS code, are there any questions?
#pngpic{width:100%;height:200px;background:url(images/alpha.png) no-repeat;_background:none;_filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(src="images/alpha.png"); }
No problem
The original poster can refer to
http://www .w3cfuns.com/thread-297-1-1.html