Site-wide colour blind mode (like what GitHub does)

Proposal

GitHub now has an experimental site-wide colour blind mode for those with red-green colour blind disabilities (deuteranopia) who cannot distinguish red and green. These colours are usually used for merge requests, issues, and some labels. For example, they have replaced red (closed) with brown and green (open) with blue. I think Gitlab should consider doing similar things to help deuteranopia users too.