how to cover full background image in css code example

Example 1: set background image full screen css

#mainBackground{
    width: 100%;
    height: 100%;
    max-height: 100%;
    margin: 0;
    padding: 0;
    background-image: url("https://images.unsplash.com/photo-1487058792275-0ad4aaf24ca7?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=750&q=80");
    background-size:100% 100%;
    background-repeat: no-repeat;

}
html, body {
    height: 100%;
    margin: 0;
    padding: 0;
}

Example 2: css background image full screen responsive

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 3: 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 4: background image size css

#example1 {
  background: url(mountain.jpg);
  background-repeat: no-repeat;
  background-size: auto;
}

#example2 {
  background: url(mountain.jpg);
  background-repeat: no-repeat;
  background-size: 300px 100px;
}

Example 5: background image css fill screen

.Background {
  background-image: url("Your picture name.jpg");
  background-repeat: no-repeat;
  height: 100%;
  background-position: center;
  background-size: cover;
}

Example 6: how to cover full background with css

<div id="bg">
  <img src="images/bg.jpg" alt="">
</div>