What BeMi said. There's a set of 160 (? I think - it's been ages since I coded anything) colors, called "web-safe" meaning they are usable and recognizeable by web browsers.
When you freshly intall a new computer, there's a certain set of fonts on it that the computer and the programs within can reach to and work with it, let's call them defaults. These fonts fall into two most basic categories - serif and sans-serif - that later divide and divide into oblivion. When you code a website, you generally state a desired font that you want to appear on the site, then a font of the defaults installed on every computer in case your specific isn't available, then a general category in case even the default font isn't available (browsing web on a mobile phone, for [lame] example).
It works the same way for your O&Os. If you choose a font that you have on your computer, named Super Fancy Font, it will appear correctly on your computer, exactly the way you want, because you have Super Fancy Font installed on your computer. I don't. So, if I view your O&Os, in order to display the page at all, my computer will supply a different font than Super Fancy Font, which will likely lead to layout problems.
So, I just wanted to advise you to stick to the default fonts, rather than some stuff that you somehow sometime downloaded from somewhere.
I've just switched to using Opera actually.
Your browser is relevant, but not all people who are going to view your O&Os will view it with Opera.
... oh the pain of optimizing.