I have a similar mindset: I had no idea how to approach Responsive Web Design. I learned Bootstrap. I now understand Responsive Web Design along with Grid Systems.
Both. I prefer using Bootstrap because I know the shortcuts, but if I need to duck down into some @media(max-width) I can. I also have a much better idea of the concept (it’s not just a lack of a fixed width; it’s changing font and element sizes and floats as you go up and down).
