I've got to be honest, the first day I was asked to use Bootstrap as a quick CSS boilerplate for a new project I just about lost my mind. I went through some tutorials and started plugging away. I'll admit I was able to get things going fairly quickly, but that was my doing--not because Bootstrap made it any easier.
CSS3 brought a new concept to us--flexbox. Everyone has largely ignored it for whatever strange reasons they have, but I've chosen to adopt the future and shape it. Let me introduce you to Flexgrid, the crazy simple CSS layout model that you should use for everything. If you want to read up on flexbox before you get started, let me direct you to CSS-Tricks.