You have to create a seperate style for the navigation links with class attributes.

So for all the links on the page you have something like:

a
{
color: red
}

a:hover
{
color: white
}

Then, for the navigation links, you create classes:

a.nav:hover
{
font-weight: bold
}

edit: oops, I didn't finish.
Then, around the text in the navigation menu, you put:
<span class="menu"></span>

There ya go!