@dosbiner With css grid you will have the problem with browser support. There are still those strange people out there, who are using something like IE11 or worse. Wouldn’t recommend that.
Bootstrap is just fine. Everyone knows it, so there are plenty of people who can modify it without much to learn. Also it is a mature framework, hat just works everywhere. It only needs an update. Maybe there is some kind of modernizer script, that can make it backwards compatible. Like jquery-migrate or modernizer.js.