To change the background picture size

Background picture was covering the entire screen but picture lost it's original form. (top blue half was rendering at the bottom as well)
Showing the image only once is specified by the background-repeat property:
background-repeat: no-repeat;

Once we made these changes the entire picture was rendering fine but the bottom half of the screen was white( screen size is bigger than the picture size)
Defined the height of the background image:
min-height: 1000px;