The div element below would usually be a 3em square. A -o-transform: scale(2.5x); scale is applied to scale the element up two and a half times, or 7.5em. The scale origin is set to -o-transform-origin: left top; so the element scales from the top left corner of the element. If the transform-origin was left at the default 50% 50% (the centre point of the element), the element would have scaled out from the centre point so that the div would overlap this paragraph and be displayed partially off the left hand side of the page.