For the uninitiated, flexbox can be used pretty much everywhere these days. That is assuming you’ve stopped supporting IE9 and below. (#protip You should stop). Can I Use shows just how well supported it is.
This is where flexbox comes in. Yes, you could use tables, but they suck too.
Flexbox is made for situations like this. Take a look at the example below. The code is exactly what I use for the Projects page here, but I have omitted the many prefixed properties for brevity.
See the example on Codepen.