Not by a long shot actually. The biggest problem with CSS grid systems is they push layout rules back into the HTML where it doesn’t belong. CSS was developed to get styling markup out of the HTML, putting it back in via classes is a bit wrong headed. But then there’s the pragmatic side of the coin - it does save a lot of time despite not being ideal.
Also, note the following:
div:after
is wrong. it’s
div::after
The single colon implementation works on IE 8 and the other browsers tolerate it, but the markup is incorrect all the same. Also, floating things around is far less useful than using a proper flexbox model. IE 9 and 10 have a smaller market share than 8 in many areas, so skipping them as well is becoming an option thank goodness.