css background always full code example
Example 1: make background full on every screen css
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;
}
Example 2: how to cover full background with css
<div id="bg">
<img src="images/bg.jpg" alt="">
</div>