What if this thing shows up in 18 places, some of those change sizes on mobile, some of them in turn being reused in several places and then somebody changes something that affects the size (and therefore desired styles) of some but not other of those contexts, and adds 6 more contexts in which the size matters?
I want to say "When displaying a user profile, If there's more than X units of horizontal space, use the large profile image. If there's more than Y units of vertical space show their bio, trimmed to length but avoiding widow sentences and followed by ellipsis. If there's very little room at all, just show their user name."
I know what I want and I can describe it simply and in a way that a machine could implement, but using today's tools it will take significant developer (human) effort (which typically isn't within my client's priorities and ultimately gets neglected).