how to set background image size to size of browser code example

Example 1: how to cover full image in css

body {
  background-position: center;
  background-repeat: no-repeat;
  background-size: cover;
}

Example 2: html background image fit to screen

body {
  background-position: center;
  background-repeat: no-repeat;
  background-size: contain;
}

Example 3: how to scale a bg image acc to size of div

/* One way */
background-size: cover;

/* Other option */
background-size: contain;