Now you are teasing me. I did use javascript because of sins and cosines. I think, now I have something, I need to step up to do it entirely in CSS. Another day will be wasted on that...

The pyramid also has layers and an initial routine where the layers get added, with a carousel made from details/summary elements to describe the layers. Clicking on the layers opens the respective details/summary and the colour changes.

The shading of the pyramid was particularly hard, since that changes as it rotates. I will have to do that in CSS too...

It's possible to have simple animation only in SVG but you can add CSS to have complex ones.