I've been dabbling in HTML and CSS since I was 13 years old! I can't imagine my life without it. All of this is hobby stuff, though I've also worked as a front-end Angular developer for a year and a half, which was fun too. Please look around on the sites listed! They are probably completely in Dutch but browsing should still be possible for anyone ;)
Tiger Teeth is fairly tame code wise - I updated most of the look of the forum with CSS only. The most notable things are the header, the account profile (really happy with that one!), the mini-profile on posts and the stat box at the bottom of the page. Overall I'm happy with the consistent style of the site and I think it's good proof that you don't need a million fancy scripts running for a site to look good and work well.
on Ilias I challenged myself to improve the experience for both the mods and players as much as possible. It has several Javascripts running to automatically load in things like lists of Pokémon of a specific type, information about moves, and there's a random Pokémon generator in the works. I overhauled the style of the thread page, the logged in userbar at the top of the page, the user profile, and a lot of other elements spread across the layout. Coding for Ilias helped me realize that I know more than just CSS and HTML and that I can celebrate what I can do even if it's still tame in comparison to others.