Great news, CSS-Tricks released their super useful Grid and Flex guides as freely downloadable posters!

Posters:
Flex: https://css-tricks.com/wp-content/uploads/2022/02/css-flexbox-poster.png
Grid: https://css-tricks.com/wp-content/uploads/2022/02/css-grid-poster.png

Guides:
Flex: https://css-tricks.com/snippets/css/a-guide-to-flexbox/
Grid: https://css-tricks.com/snippets/css/complete-guide-grid/

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