Dark theme on the web

Not to be confused with dark web.

YouTube (Classic)

• Firefox addon for forcing YouTube Classic mode
• Stylus theme

Google

• Stylus theme

Github

• Stylus theme (extra list for github.community)

Stack Overflow

• Stylus theme

Reddit (old)

Reddit Enchancement Suite allows dark theme, also for Old Reddit. If you want to force your browser to use Old Reddit interface (available at old.reddit.com), check out my Redirector List.

DuckDuckGo

Use this guide

Instagram

• Stylus theme

Other sites

• php.net

Firefox tweaks

Shadowfox

Firefox addons

• Stylus dark theme

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Some other tips and links

• Dark Reader addon for Firefox (repo)
• My Firefox recommendations
• My uBlock Origin recommendations
• Amp2Html - Addon for Firefox to redirect Accelerated Mobile Pages (AMP) to normal pages.
• FOSS-Android - List of free and open-source alternatives to proprietary Android apps.