Haha I know. Just take my word for it! Yes. Period! I'm kidding. I used fixed pixels because it was easy if you want the honest truth. I'm aware that the future is all about mobile-first but this started out as a teaching tool for myself and fixed widths is what I chose back then. I know fixed widths aren't cool but its a work in progress. I was compelled to finally share something instead of always using things others had made. Eventually it'll come with a variety of grids to choose from.