background url full size code example
Example 1: how to cover full image in css
body {
background-position: center;
background-repeat: no-repeat;
background-size: cover;
}
Example 2: how to set background automatically with my screen height
body {
background-image: url("img_tree.gif");
background-repeat: no-repeat;
background-attachment: fixed;
background-position: top center;
background-size: contain;
}