How to make full screen background in a web page

its very simple use this css (replace image.jpg with your background image)

body{height:100%;
   width:100%;
   background-image:url(image.jpg);/*your background image*/  
   background-repeat:no-repeat;/*we want to have one single image not a repeated one*/  
   background-size:cover;/*this sets the image to fullscreen covering the whole screen*/  
   /*css hack for ie*/     
   filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(src='.image.jpg',sizingMethod='scale');
   -ms-filter:"progid:DXImageTransform.Microsoft.AlphaImageLoader(src='image.jpg',sizingMethod='scale')";
}

um why not just set an image to the bottom layer and forgo all the annoyances

<img src='yourmom.png' style='position:fixed;top:0px;left:0px;width:100%;height:100%;z-index:-1;'>