Use when reviewing templates, rendered HTML, or shared components related to Create a custom 404 error page. Validate the final browser-facing markup, not just the source framework abstraction.
Install
npx skills add thedaviddias/Front-End-Checklist --skill 404-pagenpx skills add thedaviddias/Front-End-Checklist --skill 404-page -a claude-code -gnpx skills add thedaviddias/Front-End-Checklist --skill 404-page -a codex -ggemini skills install https://github.com/thedaviddias/Front-End-Checklist.git --path skills/404-pagegh skill install thedaviddias/Front-End-Checklist 404-pagegit clone --depth 1 https://github.com/thedaviddias/Front-End-Checklist /tmp/thedaviddias__Front-End-Checklist
mkdir -p ~/.claude/skills ~/.agents/skills
cp -R /tmp/thedaviddias__Front-End-Checklist/skills/404-page ~/.claude/skills/404-page # Claude Code
cp -R /tmp/thedaviddias__Front-End-Checklist/skills/404-page ~/.agents/skills/404-page # Codex, Cursor, Gemini CLI, Copilot, OpenCode