Duplicate @keyframes names resolve last-wins across the whole cascade, so
every definition but the last was dead code that still read as live at its
call site. Two of the five duplicated names differed from the winner:
fadeIn style.css had an opacity-only variant before the one that
adds translateY, so every consumer was already sliding
research-pulse a background-colour pulse sat before the opacity/scale one
that actually runs
The other three (spin, loading-bounce, pulse) were byte-identical repeats.
Removing the losing definitions changes nothing rendered, which the computed
style snapshot confirms: the committed baseline is reproduced exactly across
all three pages and 24 variants. Deciding that a consumer wanted the plain
fade, or the background pulse, would be a visual change and belongs in its own
PR with screenshots.
This also unblocks the mechanical stylesheet split. While two definitions of a
name differed, neither could be moved: relocating either changes which one is
last, and therefore changes behaviour. A regression test now fails on any
duplicate name so the trap cannot come back.
