Useful links for CSS resources
Docs
https://www.w3.org/Style/CSS/specs.en.html
Codrops CSS Reference
https://tympanus.net/codrops/css_reference/
Cheat sheets
https://adam-marsden.co.uk/css-cheat-sheet
CSS Grid
https://css-tricks.com/snippets/css/complete-guide-grid/
CSS Flex
https://css-tricks.com/snippets/css/a-guide-to-flexbox/