Simulate Zooming (doesn't change the browser's zoom level)
transform: scale(2);
-webkit-transform: scale(2);
-webkit-transform-origin: 0 0;
-moz-transform: scale(2);
-moz-transform-origin: 0 0;
-o-transform: scale(2);
-o-transform-origin: 0 0;
-ms-transform: scale(2);
-ms-transform-origin: 0 0;
Source: http://cat-in-136.blogspot.com/2010/09/unofficial-css-property-zoom.html
IE 7 and 8
zoom: 2;
These two styles may conflict, so I would suggest using a conditional comment for IE 7 and 8.
http://www.quirksmode.org/css/condcom.html
Source: How to Increase browser zoom level on page load?