Modifications for 4.3.0

[TBG-FR]

Some CSS modifications to fix things that have been broken by RC 4.3.0 😉 Thanks to @ae5960e8-a6fc-491f-b252-898ecf59af95 for pointing some of them in #161

• Left sidebar menus (Account, Display) colors (background, text, hover)
• Message option menu (three dots) colors (hover)
• Modals
  • Close button (cross icon on top right) color (hover)
  • Cancel button (when .rcx-button--ghost class is missing) color (text) (-> #144 )
• 2FA codes display box in Account menu (background)
• ...

Don't hesitate to tell me if you find something wrong or not working as expected !

[TBG-FR]

My pleasure ! 😄

I think we'll also have to clean the CSS file because a lot of css classes are gone with 4.3.0, but I think it's better to do it in another PR, after having a fully working dark theme

[pbaity]

@TBG-FR This is looking great so far, thanks so much for these fixes! Just tag me on here when you're ready for a final review and merge.

[TBG-FR]

@pbaity I think we're good, you can merge and I'll open another PR if I find anything else ;)