This here is the key.

While each site differs in various ways, a user style sheet becomes the great equalizer. You can set all of the attributes for a site as you wish, at a minimum you can set the background, foreground, and link colors, as well as the font sizes. And barring some site with automated javascript running around "fighting" you, there's nothing the site can do about it.

Now, by doing so, you may well have impact on other aspects of the site (notably overall formatting). But you can easily see the consequences of this by simply "zooming" the pages now. Most, if not all, of the browsers, have a zoom capability that boosts the font sizes of the entire page (on the Mac it's Cmd-+, it's likely Alt-+ on other machines).

There are addons, such as Grease Monkey for Firefox, that will automatically apply these changes for specific websites. So you can tweak once and keep the formatting.

In forums, folks should avoid changing colors, and letting the forum do the work for them. The major reason is that some forums have themes, which controls all of the colors. On one forum I frequent, someone likes to use blue text. Well, that may look great on his light theme, but it's impossible on my dark theme.

I don't know if our version of the forum software supports themes, or if they're enabled. If it did, perhaps Mike will make a BDD theme for you. (We don't seem to support themes right now, at least not from the Control Panel.)

But until then, add ons like Grease Monkey can help you greatly I think.

The issues you are having are a primary use case for CSS.

I'm sure if you need any help, many of us would be more than glad to assist you.