Needing a full feature programming language for things purely related to the page aesthetic is not a great idea.

The reasoning: some hosting platforms allow you to personalize your personal page changing the HTML and CSS bits, but not the JS - for security reason, obviously. Itch.io is an exmaple of that, where you can personalize your game and profile. By using CSS animations I can create cool effects without any of the security concern that allowing access to JS gives me. It makes sense and it's nice to be able to do so.