Learning HTML and CSS can be addictive! Now that you know the basics, you have the power to build anything! It’s just a matter of learning more about the details.
You can learn a lot about web design by using your browser’s built-in tools. Here’s how to do that with Google Chrome; similar tools are available for Firefox and Safari.
The LinkedIn Learning class CSS Essential Training will introduce you to modern web design practices. (You have free access with an LAPL card.)
You can work through the LinkedIn Learning path “Become a Front-End Web Developer” if you want to really hone your front-end skills.
If you like learning from books, UCLA offers you access to a HUGE collection of technical ebooks. The site even offers you “learning paths” and “playlists,” so you can work through skills methodically.
Because CSS and HTML have gotten so complex, developers often work with “frameworks” to simplify the process of organizing site development. You’ll want to learn about them.
Modern web designers often work with content-management systems (like WordPress or Drupal), so you’ll want to learn about them, too.
Modern websites make use of a lot of JavaScript, so why not learn that, too?