Yes, the css with higher Specificity will apply over other.
In this case since you replaced.table-container with your class, both have the same Specificity
so simply adding in an other class will be enough .psc-modern-table .table-container .t .tc.tc-expand
Its very weird ignition added an !important in their style though... That is concidered bad practice, especiaally for something we are supposed to be able to edit. First time ive seen it though, must have been a oversight of the css'er
Okay, so it's been this way for a long time, but the educated guess from a more Perspective focused dev is that the hardcoded size is (or was) important to the column logic. But, there is already a ticket to relax that constraint/make the expansion area more customizable, so I've added this thread to that ticket.