[Tails-dev] [review'n'merge] Unsafe browser color

Hello, the unsafe browser page say it's in red and yellow. Currently
it's only in red. I made a branch to change the page.
Please review and merge.

Repo: https://git-tails.immerda.ch/xin/tails/
Branch: unsafe_browser_color
Last Commit: cd98c71437361a957b95a64dc3c5926a4191ab8e

Cheers.
xin