A guide to CSS flex.
What Happens When You Create A Flexbox Flex Container?
https://www.smashingmagazine.com/2018/08/flexbox-display-flex-container/
A Complete Guide to Flexbox
https://css-tricks.com/snippets/css/a-guide-to-flexbox/
Everything You Need To Know About Alignment In Flexbox
https://www.smashingmagazine.com/2018/08/flexbox-alignment/