Firefox Multi-Account Containers:
sandbox tab containers to isolate sites.
https://addons.mozilla.org/en-GB/firefox/addon/multi-account-containers/
Temporary Containers:
Open tabs, websites, and links in automatically managed disposable containers
https://addons.mozilla.org/en-GB/firefox/addon/temporary-containers/
Dark Background and Light Text:
dark mode all the things
https://addons.mozilla.org/en-GB/firefox/addon/dark-background-light-text/
@Justly0250 i remember seeing something about it somewhere but i've never used anything like that