Changing SOME font sizes but not all

I would like to increase the size of some of the smaller fonts. Ive noticed that all the text in my category descriptions is tiny. I see at the very top of stylesheet.css:

body {
margin: 0;
font-family: Georgia, Times New Roman, Times, serif;
font-size: 62.5%;
color: transparent;
background-image: url(../images/sbj_logo_2.png);
background-color: #DCDCDC;
}
changing this will only change the ENTIRE document. I would like to know how to raise the size of the smallest fonts. I believe the default size of the font is set to 8pt but then that is decreased to 62.5% of that by this property. Where can I change the default size of just the smallest font?

I'm a newb (but I AM learning quickly).

If you have the Firefox browser with the webdeveloper add-on, you can see what the class and ID of each element and separate it out in the stylesheet.

I did get the add-on for my firefox but I'm not exactly sure how to use it. For example, here is the info for my text on the "create new account" box.

html > body #loginBody > div #mainWrapper > table #contentMainWrapper > tbody > tr > td > div #loginDefault .centerColumn > fieldset .floatingBox back > div .information
If I click on the text, the box comes up and says "no style information". I'm not exactly sure where to find out the statement that defines the size of this font using this add-on. Could someone clue me in here?

still requiring assistance please.....

It would be easier if I could see the text myself. When I checked earlier, the store was down for maintenance. Now, I'm getting a 404 error. :(

Sorry about that. On the off chance that someone manages to stumble into my store, I don't want anyone trying to set up an account before it's complete. I'm building the site on my local machine before final upload. I can turn the maintainance off for now so you can check it out.

Fair enough. What specific text are you concerned about? How about a screen shot? Maybe I can check on something I'm working on and see what the issue is. I know you said some of the text seemed a bit small.

Well, for one thing, I changed the size of the text in the headings of the sideboxes, but the search box heading size did not change. Where can I find that and can you tell me how to find that info using the firefox add-on please?

it will partly depend what side you have the search on, but if you add font information to rightBoxHeading and/or leftBoxHeading it should handle all of them (sideboxes) the tag for the search header specifically is searchHeading

as far as using webdevoloper once you are on the page you wish to inspect, click information, display anchors or display id & class details if you don't think it will confuse you