Well, if it's Web developer you have (Firebug is similar) select in the menu... Tools/Web Developer/CSS/View Style Information and click on any element on screen. The stylesheet pops up in about half the browser window.
I see when I click on the word Home, or the larger box around Home and Log In, that I get some of the generic link styling. But when I click to the right of them in the larger box (identified in the Web Developer bar just below the address bar as #navMainWrapper) the colours are being defined there. Start by changing that one (in stylesheet.css) to your preferred colour. You may need to add extra definitions for the active, visited and so on styles just for navMainWrapper too.
You can do the editing right there on screen until you're satisfied, then copy your changes and paste them into the real stylesheet.css file and upload it to the server to make your changes permanent. In other words, you can live-edit, but your edits aren't being saved by Web Developer.
Rob
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