Change the `lime` color in donate to #EFB149

Context: donate-static#47 (closed)

I need to make this change for the donate-static issue above. Merging this into master will break new builds of donate-static until I merge the donate-static changes. I wanted to make an MR before pushing it, so that someone else could look it over. I don't want to break the donate-static builds with bad css.

If it looks good, I can push it to master, and then push the donate-static changes.