Table of contents website examples
https://diveintohtml5.info/table-of-contents.html
https://www.tipsandtricks-hq.com/simple-table-of-contents-toc-using-pure-html-and-css-code-9217
https://diveintohtml5.info/table-of-contents.html
https://developer.mozilla.org/en-US/docs/Web/CSS/list-style#Specifications