How does one change the font sizes for the entire site?

Xoops 2 uses CSS extensively to control the look and feel of your website. If you look in /themes//style.css you will see all the styles defined for your site

If you are using the default theme you will see these two lines right at the top:

body {color: black; background: white; margin: 0; padding: 0;}

table {width: 100%; margin: 5; padding: 5; [b]font-size: small[/b]}

The bolded text above sets the font-size to small for every text within a table.
You can change this value like so:

Using pixel sizing:

table {width: 100%; margin: 5; padding: 5; [b]font-size: 10px;[/b]}

It is important to remember the px after the font size. Some browsers will ignore this style if omitted.

Using absolute font size keywords:

table {width: 100%; margin: 5; padding: 5; [b]font-size: large[/b]}

The absolute font sizes:
xx-small | x-small | small | medium | large | x-large | xx-large

Once you get beyond certain browser's inconsistencies (* cough, cough, IE 5.x, NN 4*), CSS is a very powerful tool to quickly modify an entire site's appearance.

More Information:
W3school's CSS School
Style Master's CSS Tutorial
CSS Tutorial at HTMLHelp.com

A little more, from my somewhat limited experience with XOOPS themes and their CSS files:

What I do is put something like this in style.css:
Quote:

Then, in styleNN.css (for Netscape browsers), I put this:

Quote:

Everywhere else in my style files, I specify font-size only as a percentage. Nowhere do I specify font-size in points or pixels.


For example:

Quote:

This has the effect of getting almost exactly the same fonts in both browsers, and what's more the user can scale the fonts (with Ctrl+ and Ctrl-) and all the fonts scale together.

Your milage may vary, but this works for me.