http://www.jeasyuicn.com/css-background-image-stretching.html
background-image:url(bg.png);
-moz-background-size: 100% 100%;
-o-background-size: 100% 100%;
-webkit-background-size: 100% 100%;
background-size: 100% 100%;
-moz-border-image: url(bg.png) 0;
background-repeat:no-repeat\9;
background-image:none\9;
filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(src='bg.png', sizingMethod='scale')\9;