The transition between the collapsed and open state of details is very sudden. From a visual perspective, this makes the interface feel very blunt rather than smooth.
I suggest that we add a very small transition between open and closed state, having it collapse. This should be doable with CSS only, and we have to make sure that we do this collapse within the "noticeable" but not causing it to feel slow. This should be easily do-able, and now that we don't need JS for this anymore - it seems like a feasible objective.
Screenshot of where to find a <details> element.