HTML - header background

by yeyene

HTML

<div id="header">I am Header</div>

CSS

body{
    margin:0;
    padding:0;
}
#header{
    float:left;
    width:120em;
    height:5em;
    background:url(http://2.bp.blogspot.com/-YUUHSmN2iKc/URqH5KMr6OI/AAAAAAAABpE/ta3lwt2KDx8/s1600/desktop-wallpaper-1600x1200.jpg);
    -webkit-background-size: cover;
  -moz-background-size: cover;
  -o-background-size: cover;
  background-size: cover;
}