CSS is a superpower
I was recently reminded just how much time some web-dev teams are losing every day through lacking CSS knowledge. Things that would take an experienced CSS dev a few hours are costing some teams days.
It's not just writing the CSS in the first place either. People have a habit of fixing CSS problems by adding more CSS, and over time this often ends up in an unmanageable mess. Getting the structure right from the beginning is difficult but making sure it stays on track is harder still. Having somebody in the team who knows CSS well means they can design a structure to mitigate this problem and avoid the long-term CSS issue.
Honestly, if you want to be a front-end dev then learn CSS. It's a superpower.