Hi--I'm just starting out with C5--took the plain vanilla theme, copied it to a new directory in /themes, edited the main stylesheet, etc. Then I tried using the dashboard customization to change colors on links & hovers, but the customization page for my new theme had two color pick-boxes, only one of which I could change, and the changes never stuck.

The problem was in how I named stlyesheet backups; when I made the first few tweaks, I copied main.css to main.css.orig in the themes directory, and had another copy named main.css.bak. When I renamed the backups something less parallel, like hold-maincss.orig & hold-typographycss.orig, the problem went away. Word to the wise!

Daniel