I tried some of the examples. The UX for seeing the different designs is terrible.

1. Go to site

2. Visually scan the page for the style controls

3. Click one

4. Everything changes

5. Visually scan the page for the style controls etc.

I dont want to visually scan every time I change the stlye.

https://csszengarden.com/216/

https://www.csszengarden.com/pages/alldesigns/