compozy Web Prototype Skill
Produce a single, self-contained HTML prototype using the bundled seed and layout library — not by writing CSS from scratch. The seed already encodes good defaults (typography, spacing, accent budget). Your job is to compose it.
Resource map
web-prototype/
├── SKILL.md ← you're reading this
├── assets/
│ └── template.html ← seed: tokens + class system + chrome (READ FIRST)
└── references/
├── layouts.md ← 8 paste-ready section skeletons
└── checklist.md ← P0/P1/P2 self-review
Workflow
Step 0 — Pre-flight (do this once before writing anything)
- Read
assets/template.htmlend-to-end — at minimum through the<style>block. The class inventory at the top ofreferences/layouts.mdlists every class that must be defined there; if one is missing, add it to<style>rather than re-defining it inline on every section. - Read
references/layouts.mdso you know which section skeletons exist. Don't write a section type that isn't covered — pick the closest layout and adapt. - Read the active DESIGN.md (already injected into your system prompt). Map its colors to the six
:rootvariables in the seed; don't introduce new tokens.
Step 1 — Prepare the artifact from the seed
Choose one kebab-case artifact slug before composing the page. Use assets/template.html as the seed for the final artifact HTML.
Do not write a project-root HTML draft with file-write before emitting the final <artifact>. The live-artifact output is the canonical HTML file for this generation turn; an extra index.html, cast.html, or brief-derived draft can be stranded beside it as an orphan.
Replace the six :root variables with the active design system's tokens. Replace the page <title> and the topnav brand.
Step 2 — Plan the section list
Pick layouts before writing copy. Default rhythms (from layouts.md):
| Page kind | Default rhythm |
|---|---|
| Landing | 1 hero → 3 features → 4 stats or 5 quote → custom split → 6 cta |
| Marketing / editorial | 1 hero-center → 7 log list → 6 cta |
| Pricing | 1 hero-center → 8 comparison table → 6 cta |
| Docs index | 1 hero-center → 7 log list (sections of docs) → 6 cta |
State the chosen list in one sentence to the user before writing — they can redirect cheaply now and not after 200 lines of HTML.
Step 3 — Paste and fill
For each chosen layout, copy the <section> block from layouts.md into <main id="content"> of the artifact HTML. Replace bracketed [REPLACE] strings with real, specific copy from the user's brief. No filler — if a slot is empty, the section is the wrong choice; pick a different layout.
Step 4 — Self-check
Run through references/checklist.md top to bottom. Every P0 item must pass before you move on. P1 items should pass; P2 are bonus.
Step 5 — Emit the artifact
Wrap the completed HTML in <artifact> tags using the artifact slug as the identifier. One sentence before describing what's there. Stop after </artifact>.
Hard rules (the seed protects most of these — don't fight it)
- Single accent, used at most twice per screen. Eyebrow + primary CTA is the default budget.
- Display font is serif (Iowan Old Style / Charter / Georgia in the seed). Sans for body. Mono for numerics, captions, eyebrows.
- Image placeholders, not external URLs. Use the
.ph-imgclass — never link to a stock photo CDN. - Mobile reflow already works via the seed's media query at 920px. Don't break it by adding fixed widths.
data-od-idon every<section>so comment mode can target it.
Output contract
<artifact identifier="kebab-case-slug" type="text/html" title="Human Title">
<!doctype html>
<html>...</html>
</artifact>
Open Design derives the canonical HTML artifact from this identifier. Do not also write another root HTML file for the same generation turn.
One sentence before the artifact. Nothing after.