If you are someone (like me) who's done CSS/Frontend 'a few years ago' do take a look at this video to see the progression. A lot of things (CENTERING!) which were much harder in the past are now complex but possible. The newer style stanzas will look alien to you.
First real forays into FE that didn't involve slicing PSDs to tables were in Bootstrap and Foundation in ~2013. The responsive grid those frameworks delivered seemed magical at the time, but you got the sense that the benefits came on the back of some serious CSS wizardry and framework overhead.
The newer CSS features (grid, flexbox) seem so light and magical.
