background-position: [ [ <percentage> | <length> | left | center | right ] [ <percentage> | <length> | top | center | bottom ]? ] | [ [ left | center | right ] || [ top | center | bottom ] ]

• Gives the initial position of the background image relative to the element
• top left says that the top left of the image coincides with the top left of the area
• If only the horizontal value is given, the vertical position is assumed to be 50%
• 20% 50% specifies that the point 20% across and 50% down the image is placed at the point 20% across and 50% down the area
• Absolute pixel values allowed
• Only allowed to have background positioning on block-level elements