Single price grid component using Grid, rem units, media queries

My feedback and difficulties mostly came from responsive design adjustments with Grid and rem units. Here's where I need feedback:

• Use of CSS Grid; I did a mobile-first workflow, and didn't implement Grid until the larger breakpoints; seems like there may have been a better way to use this and write less CSS for the breakpoints
• Use of rem units; mobile-first was fine, but then going to large screens made everything seem too small, so I made a lot of manual size adjustments in the breakpoints; again, feels like there would have been a better way to master rem (and maybe em) units so that the size adjustments happen automatically for breakpoints

Otherwise, I welcome feedback about any other observations. Thank you!