For those not aware, Zulip has been polishing it's UI to make it feel fresher - yet keep the high info density it's known for.
Check it out live at the link above.
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EDIT:
What I'd love to see is Zulip:
- stop using 'globe' icons, and instead us '#' (the industry has settled on '#', so might as well embarrass it)
- update the color scheme/theme (or allow users to define their own color theme)