For the day? I guess it depends on how technical you want to get about what a screen is. I've read on a Kindle for 5 hours today, as I want to re-read this book series before the next book comes out next week. I was also flying in flight simulator at the same time, but that was 80% autopilot.
Approximations for yesterday since neither have a proper screen time counter
Phone: ~1.5 hours
Computer: ~7 hours
Kinda scary to see how many hours of the day I was seated in front of a screen. Should I feel less guilty that over 4 hours of that was spent writing documentation?
What I don't feel guilty about is screen time accrued while waiting in line. That makes me feel productive, or at least like offloading my scrolling to otherwise idle time.