“What are some HTML and CSS techniques, skills, know-how’s that are an absolute must? Just off the top of your head” – reddit user asks

What are some HTML and CSS techniques, skills, know-how’s that are an absolute must? Just off the top of your head from r/webdev

Learn Flexbox in-and-out. Whenever I can’t remember how something related to Flexbox works, this is the go-to article: https://css-tricks.com/snippets/css/a-guide-to-flexbox/