Add Light Mode/Theme

[aragubas]

Some users experience/prefer light mode, a forced dark mode is a big accessibility issue because some users (like me) can't use dark mode because we have astigmatism/other problems related to vision. Hallation is a big issue for me and causes me a headache when using it for more than 5 minutes.

[Keavon]

This is blocked on design.

It'll likely be a few more years before we can prioritize it, so you may want to look into browser extension style mods in the meantime if this is mission-critical to you. It will happen someday.