BuddyPress.org

Yes, what wilfil said will change the link color to a darker blue, but if you want more control over how dark it will be you can replace the word “blue” in his code “a {color:blue !important;}” to a hexadecimal value.

After doing a quick google search I found http://www.2createawebsite.com/build/hex-colors.html. Scroll down to the color box and after you select the color just copy and paste the hex value from the bottom right of that box. You will need to include the “#” along with the six digits that follow it in your code.

Example:
a {color:#0C19A2 !important;}

To further explain the “!important” exclamation, it just allows you to override CSS properties already assigned to an element. In this case the color property is being overridden from the default.css blue (which has already been set by buddypress) to your newly assigned color for the “a” element.

Hope this helps!