https://builtvisible.com/hand-coding-personal-website/
This isn't all that useful. But it is. It has lots of links in it.
normalize
http://necolas.github.io/normalize.css/
Responsive web design
https://alistapart.com/article/responsive-web-design
css media queries
https://builtvisible.com/using-css-media-queries-aid-site-optimisation-2/
html5 boilerplate
https://color.adobe.com/create/color-wheel/
It's also, then, an ad (affiliate links?) for a hosting company so well done to them.
It's also inspiring to me because it ranks well for the sort of searches I was making.
I can do better than that. I can write clearly.