If you do not want to use the .normal style, you can always just use:

* {font-size:11px}   <---- changes all fonts not given a specific size to 11 px

body {font-size:11px}  <---- changes all fonts in the body tag not given a specific size to 11 px

I usually strip all the built in classes out of my skins and modules.  Seems like too much markup to have class="normal" everywhere. That's just me though.

-James

Basically you have different levels of stylesheets in DNN.

Default.css
Skin.css
Module.css

There is also a portal.css, but I never use it.

The default.css can be overidden by either of these other stylesheets.  Say if you did this in the default.css file:

.Normal,.NormalDisabled
{
    font-family: Tahoma, Arial, Helvetica;
    font-size: 11px;
    font-weight: normal;
}

and then did this in the skin.css file:
.Normal,.NormalDisabled
{
    font-family: Tahoma, Arial, Helvetica;
    font-size: 13px;
    font-weight: normal;
}

your text size would be 13px in the skin that skin.css applies to, but would still be 11px in any other skin that you create later on.

and then there is module.css within all the different module..such as the Events module.  If you change the module.css in the event module to:
.Normal,.NormalDisabled
{
    font-family: Tahoma, Arial, Helvetica;
    font-size: 15px;
    font-weight: normal;
}

it would set the size of normal text in the event module to 15px, but the rest of your modules will be the skin.css font size of 13px.

You also have different choices than setting your font-size in pixels.  When you use say 11px font size, this means that the user cannot adjust the size of text with his/her browser.  It's stuck at 11px.  If you use the measurement of ems, they can adjust it. For example:

.Normal,.NormalDisabled
{
    font-family: Tahoma, Arial, Helvetica;
    font-size: 1em;
    font-weight: normal;
}

1em is basically the normal text size in a browser.  Then if the user wants to increase or decrease the size in their browser, they are able.

If I am wrong on any of this, I'm sure Nina will correct me.  Hope this helps.

Here is a link describing using ems vs pixels:
http://cssbeauty.com/skillshare/discussion/310/em-vs-px-and-why/

I'm sure you can find more doing a google search on, "em vs px".

To change your text size in Explorer:
View->Text Size->small

You can also change the text size in your browser by holding down the Ctrl key and using your mouse scroll button (if the designer used ems).

I think em came from old typography measurements of printers.  Its a relative size.  1em would be normal size. 2em would be twice the normal size.  1.5 would be in between...etc..

-James