/* spec information about this property
name= background
css1= http://www.w3.org/TR/2008/REC-CSS1-20080411/#background 
css2= http://www.w3.org/TR/2008/REC-CSS2-20080411/colors.html#background-properties
css21= http://www.w3.org/TR/2011/REC-CSS2-20110607/colors.html#background
css3= http://www.w3.org/TR/2011/CR-css3-background-20110215/#the-background
other= 
*/