How can I manipulate the browser text size with Javascript?

I want to keep the text size on the browser medium when people view my pages, but I don't know the syntax, Could someone please help me with the syntax?

Thanx,
Jon

Use CSS, i.e in your head

<style>
body{color:FFFFFF;font-family:arial,verdana;font-size:12pt;}
</style>

I think you can also set the font-size in 'pt' or 'em(s?)'

Thank you very much, I use style tags all the time, but i never really looked at what they did. I thought you could still manipulate the font with the browser even if you set the font size with a style tag, but you learn something new everyday.
Thank you again,
Jon