set background to 100 height and width in css code example

Example 1: how to set background image 100 height

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 image height and width

.class{
	background: url("../images/icons/map.png") no-repeat center center/50px 50px fixed;
}