/* spec information about this property
name= z-index
css1= NA 
css2= http://www.w3.org/TR/2008/REC-CSS2-20080411/visuren.html#propdef-z-index
css21= http://www.w3.org/TR/2011/REC-CSS2-20110607/visuren.html#propdef-z-index
css3= NA
*/