Make Slack fit in better as a web panel for Vivaldi. More information in the text block following this. All code available as public domain via Creative Commons CC0.
The file upload button annoyed me, so I centered it.
Added theme support, covering Slack’s default eight themes and repurposing the middle section for people who use a “Custom” theme. If applying a more extensive theme from userstyles.org then slightly change the colour of your present theme to make it “Custom” so the values defined in the variables at the second section are applied. Custom unread colour support also applies to unread banner and highlight.
Open User CSS release: I figured out some way to exploit Slack’s magic with the header to produce an improved version of the mod which positions the close button over the menu button, by making the act of having any right panel in effect <b>remove</b> the menu button until closed. This fixes the issue wth close button not appearing in the threads right panel menu.
Also made it so the toggle at the updates right panel is decorated, due to how this style handles the right side header, and added variables to change the colour of this for use with other themes from here and Open User CSS, where this style will be made available.
I goofed and forgot some semicolons. Also added screenshot from the original style.
The threads close button was messed so I fixed that.
Reverted dates again because OUCSS broke. Fixed some aesthetic things and added some other enhancements to the sidebar.
Actually applied the fixes I promised, because earlier I was an idiot and mismanaged my code. Incompetence resolved.
Last-minute beautification; Fixed modal header appearance for Slack settings, slightly repositioned another out-of-place close button and made sidebar visible while previewing themes.
A preview of options you can set in your extension