Creating an Interactive Cartoon using HTML/CSS/JS

I've always been amazed by what few people can do with CSS. They are truly artists, and that's what inspired me to make this.

It's extremely simple, honestly noob-level, but I felt if anybody else wanted to get into the CSS artistry zone, this would be a great tutorial pen to see what makes everything work the way it should.

I had so much fun making this, and maybe I might make a few more. Any suggestions on libraries to use that might make my life easier? Any CSS tricks to drawing perfect detailed faces? I'd love to hear your inputs.