A 404 built from the ZX Spectrum's real colour-cell attribute clash: each 8x8 hardware cell could carry only one ink/paper colour pair, so image detail finer than the cell budget visibly bled and blocked. This translates that as a monochrome glyph+weight budget (one glyph and one font-weight per cell), so the numerals' own curved edges snap and bleed at the seams, with a rolling scanline that re-decides a handful of rows per frame like attribute RAM racing the beam.
pnpm dlx shadcn@latest add "https://design.helpmarq.com/r/not-found-attribute-clash.json"