Mobile-first, grid and first time with sass

I originally downloaded this one over a month ago, I felt stuck on so many things, but came back to it after learning a lot more and I'm really happy with how far I've come. I found grid and the media query easier than expected, but found it difficult to get font-sizes etc to match the design for mobile and desktop. Any feedback is welcome, and any tip for using sass - not sure if there is more that I could have done other than colors? Should I have more than one media query?