Frontend Mentor - Huddle landing page with single introductory section

This was an amazing project to tackle. My difficulties were mostly around playing with margins and paddings and making the layout responsive, especially when setting up media query for mobile screens where my margin would appear big on one side and I wasn't sure where it was coming from.

I would like to ask the community to advise me on whether I used some css styling that weren't necessary and wouldn't make any difference. I tend to overlook the DRY method and sometimes I am confused with how the selectors works.