macOS Terminal.app quantises truecolor to its nearest 256 slot (so
#5e6ad2 lavender lands on slot 62 #5f5fd7, visibly more blue) and
renders \x1b[2m as a heavy multiply instead of a gentle blend, producing
the "blue border + heavy shadow" against iTerm's identical code.
Branch on TERM_PROGRAM: iTerm keeps its truecolor accent and \x1b[2m
dim; Apple_Terminal switches to pinned 256-slot accent (105) and an
explicit mid-gray (244) for dim. Box border (146) was already 256-slot
so it carries unchanged.
Yanis
8536f242ab
