There are still a lot of project website in KDE using the old KDE3 Crystal or KDE4 Oxygen theme.
List of most of the outdated website:
+ https://docs.kde.org D17936
+ https://konsole.kde.org D20701
+ https://yakuake.kde.org/
+ https://utils.kde.org
+ https://umbrello.kde.org/
+ https://solid.kde.org/
+ https://phonon.kde.org/
+ https://reqonk.kde.org (obsolete)
+ https://quality.calligra.org/ (look dead)
+ https://okular.kde.org/
+ https://necessitas.kde.org/
+ https://multimedia.kde.org/
+ https://marble.kde.org/
+ https://manifesto.kde.org/
+ https://krusader.org/
+ https://konversation.kde.org/
+ https://konqueror.org/
+ https://kmymoney.org/
+ https://kdesrc-build.kde.org/
+ https://juk.kde.org/
+ https://relate.kde.org/
+ https://games.kde.org/
+ https://freebsd.kde.org/
+ https://forum.kde.org/
+ https://evolve.kde.org/
+ https://events.kde.org/
+ https://ev.kde.org/
+ https://edu.kde.org/
+ http://michpolicht.github.io/CuteHMI/ => https://cgit.kde.org/websites/cutehmi-kde-org.git/
+ https://conf.kde.org/
+ https://choqok.kde.org/
+ https://ballot.kde.org/
+ https://accessibility.kde.org/
+ https://userbase.kde.org/
I think for most of this website jekyll could be used similar to how this was done for kontact.kde.org.