UI update

[kwiato]

No description provided.

[dgarcia360]

Feedback:

•  Page with banner looks off:

  

  You can preview it by setting the following in conf.py:

  html_theme_options = {
     (...)
     "hide_banner": "false",
  }
  

•  Some pages in Mac 13" screen introduce now an horizontal scrollbar (e.g. Getting started > Quickstart):

  

•  Left & right sidebar blinks when reaching the end of the page: https://www.awesomescreenshot.com/video/34852760?key=2e3e25b17ace471894f832094e1aea91

[dgarcia360]

LGTM!

I added some edits:

• Changed anchor icon & updated icons lib
• Anchor icon is copied on hover + click
• Add configurable brand variables in conf.py

[dgarcia360]

@annastuchlik ready for review