Positioning-offset-background-images From http://css-tricks.com/positioning-offset-background-images/ Js is most compatible
background-position: right 20px bottom 10px;
var el = $(".example"),
bgWidth = 20,
bgHeight = 20;
el.css({
"background-position": (el.width()-bgWidth+10) + "px " + (el.height()-bgHeight-10) + "px"
});
background-position: calc(100% - 20px) calc(100% - 10px);