The SVG-line replacement from the gradient-cleanup refactor (commit
635a4c3) drew the slash on the main diagonal (top-left → bottom-right)
and stopped at the inset:6px box edge — visually disconnected from the
cell vertices. The original CSS gradient stripe goes corner-to-corner
of the inset box on the anti-diagonal (the natural slash direction
for Vietnamese lô tô), with a clip-path reveal animation that reads
as "drawing" the slash.
- Restore .cell-crossed / .cell-crossed-win pseudo classes
- Replace the inline <svg> markup with a single <span> + class
- Restore cross-draw keyframes (clip-path inset reveal)
- prefers-reduced-motion: keep slash drawn, drop the reveal animation