how to adapt an image to a page in the background code example

Example 1: CSS make image fill whole background

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: background: url("image/banner-image-1.jpg") no-repeat center top; background-size:cover;

-moz-backface-visibility: hidden;