Curious if you could let me know what code or images provide the backgrounds on your Kakuro, is it a CSS diagonal line, or a tile? What comes up if you run a quick:
find . -name diag.png -type f
Reminds me of mine!.kakuro-clue { background-image: linear-gradient(to top right, transparent calc(50% - 0.5px), rgb(148 163 184) calc(50% - 0.5px), rgb(148 163 184) calc(50% + 0.5px), transparent calc(50% + 0.5px)); }
The site uses Tailwind CSS for the styling generally.
EDIT: just played a hard game, and genuinely made a mistake. Having it tell me immediately definitely was cheating as there was then only one other answer that square could have been.