You can change the color theme from the setting page under the top right drop-down. But it would be nice to have something like Reddit Extension Suite for the default Lemmy UI front end for custom defined CSS.

I think once we get a few more third party clients to explore alternative UIs, folks should have more options for personal preference.

One thing I like about the current web UI already is the low noise in embedded text in the discussion threads. E.g. when I engage my screen reader, all I have to listen to when moving between comments is the post author and post date. Just enough context to understand the TTS engine moving between comments, unlike the old.reddit.com UI that include 5 or 6 different hyperlinked words (parent, context, permalink, etc) that the TTS has two repeat over and over again.

The hover text for icon links should be enough UI context for screen readers, although not all icon links on the current Lemmy UI seem to include hover text meta data, like the permalink chain icon 🔗, while the collapse minimize icon does.