It had ~32px of overflow causing a horizontal scrollbar. Turns out the layout engine gets confused when hidden elements are at the end of a flexbox, so we just move them higher in the DOM (where they logically still make sense).
The remaining changes are all alignment and misc changes in that respect, and probably not obvious.
The tag options are not implemented out of concern for diff size.
This splits the context menu classes out to a new "iconized" style which is common across a number of context menus, including the UserMenu.
Some of the badge/sublist styles had to change to better accommodate the menu icon lining up.
This also contains the framework required for https://github.com/vector-im/riot-web/issues/13961
Michael Telatynski