The body assumes Claude's competence (references "CSS Grid", "sticky positioning", and logical CSS properties without explaining them) and every section earns its place, avoiding restating concepts Claude already knows.

Concrete numeric constraints (240–280px nav, 200–240px TOC, max-width ~720px, 3–5 groups of 4–8 links, 350+ words, one 5–15 line snippet) plus a precise output contract make the guidance copy-ready and specific.

A clear six-step sequence ends in an explicit self-check (line-length, mono token, accent restraint, responsive collapse, logical CSS) that serves as the validation checkpoint for this generation task.

No external references are needed and none exist; the body is organized into tight Workflow and Output contract sections, which per the scoring notes earns a 3 for a self-contained skill.

"inline-start nav, scrollable article body, inline-end table of contents" names multiple concrete structural components of the deliverable rather than vague language, matching the 'lists multiple specific concrete actions' anchor.

It explicitly states what (a three-column documentation page) and when ("Use when the brief mentions ..."), satisfying both halves of the completeness anchor with explicit triggers.

"docs", "documentation", "guide", "API reference", "tutorial" (plus the frontmatter trigger "文档") give good coverage of natural terms a user would say, matching the high-coverage anchor.

The documentation-page niche with concrete layout triggers is clearly distinguishable and unlikely to fire for unrelated skills, matching the 'clear niche with distinct triggers' anchor.