This should be a fork of currently used theme for hig.kde.org: https://sphinx-rtd-theme.readthedocs.io/en/stable/.
The theme should have some visual similarity to the Aether theme (kde.org) and have some stong KDE branding.
Websites that could use this new theme are:
* hig.kde.org
* the Kirigami documentation
* the KDE System Administration documentation