Mastodon now supports automatic switching between the light and dark theme, depending on your system setting.

It will be available in the upcoming 4.3 version, or is already there if your instance runs the nightly code.

You can switch to this new automatic theme in your Appearance preferences. Instance admins can also set it as the default theme (I just did it on mastodon.social and mastodon.online).

This has been done in https://github.com/mastodon/mastodon/pull/29748, thanks a lot to @nshki for the initial PR!

Support "system" theme setting (light/dark theme depending on user system preference) by renchap · Pull Request #29748 · mastodon/mastodon

This is built on the work by @nshki in #20107 I rebased it, made the emoji selection code simpler and ensure it uses a consistent theme: in the web UI, the user setting is used, falling back to th...

GitHub
@renchap
Hi, when is V 4.3 due? I'm asking because of the URLs in the preview cards. Will they be fixed?
@mho Is there an issue for this?
Change link previews to keep original URL from the status by Gargron · Pull Request #27312 · mastodon/mastodon

Fix #27056, fix #21308, fix #19538

GitHub
@renchap
And? Any news on this?
@mho it has been merged, so it will ship in 4.3. Current target is a release in 6-8 weeks