CSS
https://www.makeuseof.com/tag/simple-css-code-examples/
https://www.bitdegree.org/learn/css-display
https://www.tutorialrepublic.com/codelab.php?topic=css&file=fixed-positioning
https://www.w3schools.com/css/css_website_layout.asp
HTML+CSS
https://internetingishard.com/html-and-css/basic-web-pages/
