.sky {  background-image: url(images/sky.jpg); background-repeat: repeat-x}
.screen {  background-image: url(images/static.gif); background-repeat: repeat}
.trees {  background-image: url(images/trees.jpg); background-repeat: repeat-y}
.right {  background-image: url(images/right_bg.gif); background-repeat: repeat-y}
.cars {  background-image: url(images/car.jpg); background-repeat: repeat-x}