Why do dining chairs feel wrong? Slide the table and seat to see

Why does one dining set feel right and another feel off? Mostly it comes down to two gaps: the space from your seat to the top of the table, and the space from your seat to the underside of the frame, where your thighs live.

Slide the table, the seat and the frame to see whether yours land in the comfortable range, and what cheap fixes to try before you buy anything new.