You should check out my friend Zach's Zine Library!
You can take a look at how each zine is made, you can make copies of them, and follow the helpful instructions to start customising them and making your own.
Some more resources for learning about CSS and its buddies HTML and JavaScript:
MDN Web Docs: https://developer.mozilla.org
Search for any CSS, HTML or Javascript term and you'll get an explanation and examples of what it is and how it works.
CSS-Tricks: https://css-tricks.com
Tons of tutorials to help you do fancy things with CSS!
Code Pen: https://codepen.io
Be inspired and learn by fiddling about with other people's code experiments.