Group Client Project - Javascript for controlling font size

As we realised that many software companies may have smaller computer monitors, I got the job to look up a Javascript which could control the font size in a page.
So here's the Javascript for changing the font size in the webpage.

http://www.white-hat-web-design.co.uk/articles/js-fontsize.php

I've tried it in one of the page we've got and it worked.


I've also created two icons for the changing buttons. (transparent background with white image so it doesn't show:p)