FlexBox Cheatsheet
At our company, we semi-recently sunset our support for IE10, which has enabled all of our frontend guys to start redoing a lot of our app using flexbox. It's been one of the better decisions we've made. It's such a joy to use, reduced dozens (if not many more) lines of positioning code and has facilitated moving  around so much easier. The only thing we've run into is adding "display:flex" to child elements, so that we can alter the contents direction and have rows / columns under the same parent (which has inevitably forced us to use "display:flex" all over the place).I'm looking forward to when we can move to the CSS grid stuff personally, but at this point, we haven't due to less browser support for IE11. That and we're enjoying flexbox after many years of floats.