JQuery CSS Background-position FireFox / Opera Bug

JQuery CSS Background-position FireFox / Opera Bug

I have used JQuery to change CSS styles for my Navigation Bar elements:

  1.         var imagepos = (parseInt($(this).css('background-position-y'))-30)+'px';
  2.         $(this).css({
  3.             'background-position-y': imagepos
  4.         });

Ok so after a bit of research I discovered that " background-position-y " and "  background-position-x  " are not supported by the Mozilla Firefox / Opera browsers...

Anyone know of an alternate method of getting the background-y / x positions?

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This is what I ended up using..
positionXY = $('...............').css('backgroundPosition').split(" ");

Result: 
positionXY[0]   =   X Pos..
positionXY[1]   =   Y Pos..