CSS : Relative zoom

Right now, the "zoom in" graphic is linked to an alternate stylesheet with the following css:

body {
zoom: 1.2; -moz-transform: scale(1.2); -moz-transform-origin: 0 0}
} 

This works fine, but ideally I'd like to have the link trigger a relative zoom rather than an absolute zoom value -- so i would need to establish a variable that determined the user's current zoom level, and then increase that zoom by 120%. This way the same link could be clicked multiple times to increase the zoom incrementally.

Other Topics

CSS : Background colour running to the screen bottom,CSS : Text-transform command,CSS : IE and width & height issues,CSS : Drop down menu,CSS :  Accordion Menu: CSS coding,CSS : Zoom property,CSS : Relative zoom,CSS3 : target-new Property ,CSS : 3-d push button effect ,CSS : Document for handhelds ,CSS : Invisible text ,CSS : Disappearing text or images in IE? ,CSS : Image replacement technique,CSS : Box model hack alternative,CSS : Centre aligning a block element,CSS : Class selector,CSS : Sticky Footer Layout,CSS::STYLING FORMS, mechanical Engineering, English books,Photoshop tutorials,Harry potter,Best 100 english books,Mechanical-old-question-paper,CSS : Id Selector