Full screen background image

CSS3 introduced a new property background-size that enables you to change the size of background images. That means you can stretch your image horizontally, vertically, or both. You can resize it any way you wish.

 html {
   background: url(images/bg.jpg) no-repeat center center fixed;
   -webkit-background-size: cover;
   -moz-background-size: cover;
   -o-background-size: cover;
   background-size: cover;
 }