I was on a Surface Studio, with a display resolution of 4500 x 3000 w/ 200% scaling.
It is a touch device, but I only used keyboard and mouse. My friend, who had the same issue, was on an Apple laptop.
However, I just checked again, and the problem is gone! I confirmed it on a second machine as well. It feels like there was perhaps a CSS file/rule that wasn't getting applied, or was stuck in my cache perhaps?