Flexbox
Almost complete guide to flexbox (without flexbox) : http://kyusuf.com/post/almost-complete-guide-to-flexbox-without-flexbox
The Complete CSS Flexbox Resources: http://www.cssauthor.com/css-flexbox/
Flexbox For Interfaces All The Way: Tracks Case Study: https://www.smashingmagazine.com/2015/11/flexbox-interfaces-tracks-case-study/