Hallmark

Hallmark is an open-source design skill made by Together AI, installable into Claude Code, Cursor, and Codex via a single npx skills add command. It encodes opinionated anti-AI-slop design rules — covering typography, colour, layout, motion, and microinteractions — into a structured ruleset that AI coding assistants will follow when generating UI. The project is MIT-licensed and hosted on GitHub under the Nutlope/hallmark repository.

What It Is

Hallmark is a "skill" — a rule file that attaches to an AI coding assistant and changes how it generates front-end UI. Rather than letting the model reach for its trained defaults (purple-to-pink gradient heroes, Inter as both display and body font, centred-everything layouts), Hallmark intercepts the design decision and routes it through a six-step flow: read the brief, pick a macrostructure from 21 named whole-page shapes, apply one of 22 themes across four genres, run a 65-gate slop test, and emit a stamped, working page. The core rule-set lives in SKILL.md and a references/ directory of opinionated sub-rules.

Four Verbs and What They Do

Hallmark exposes one default behaviour and three explicit verbs:

• Default — build new UI from a brief; asks for audience, use, and tone; picks macrostructure and theme; runs the slop test before returning.
• hallmark audit <target> — scores existing code against named anti-patterns and structural sameness; returns a punch list, no edits.
• hallmark redesign <target> [--mood <name>] — discards the structure, keeps copy and information architecture, rebuilds with a deliberately different fingerprint.
• hallmark study <screenshot | URL> — the differentiator; extracts design DNA (macrostructure, type-pairing, colour anchor) from a screenshot or live URL; image mode names font roles without guessing font IDs; URL mode reads HTML/CSS via WebFetch and names exact fonts and tokens; refuses paid templates and competitor pages outright.

The Slop-Test Architecture

Before every output, Hallmark runs 65 named gates. A single "yes" fails the build. Gates cover typography discipline (max three font families per page), input-state correctness (focus ring via outline not border, helper-text slot reserves height), APCA/WCAG contrast thresholds, structural fingerprints (AI nav shape, AI footer shape, hero centred-everything), honest-copy enforcement (no invented metrics, no re-drawn UI chrome), and layout-safety checks (1fr image-track overflow, missing overflow-x: clip). The gate list has grown across versions — gates 56–60 were added in v1.0.0 and cover honest copy, re-drawn chrome, mid-render token improvisation, two-line clickable text, and emoji-as-feature-icon.

Genres, Themes, and Macrostructures

Hallmark routes each brief through one of four genres before picking a theme:

• Editorial (default) — the canonical anti-slop voice; bans radial blooms and pure-white backgrounds.
• Modern-minimal — Stripe/Linear/ElevenLabs school; allows pure white and pill CTAs.
• Atmospheric — Suno/Runway/dark-AI-tool school; allows radial blooms.
• Playful — post-Linear soft school.

Twenty-two themes are clustered across these genres (e.g., Specimen, Editorial, Atelier, Newsprint, Salon, Linen, Almanac, Garden, Studio, Sport, Riso, Brutal, Manifesto in editorial; Quiet, Coral, Violet in modern-minimal; Midnight, Terminal, Bloom, Aurora, Halo in atmospheric; Plume in playful). A per-project .hallmark/log.json records each run's macrostructure and theme so consecutive outputs in the same project don't repeat shapes.

Update: v1.0.0

The repository was created in April 2026 and last pushed in May 2026. Version 1.0.0 introduced pre-emit critique on six axes, honest-copy enforcement, locked-token discipline, a re-drawn-chrome ban, a no-wrap rule for clickable text, and five new slop-test gates (56–60). The project is actively maintained with 62 stars and 3 forks as of the last recorded update.

Setup Path

Installation is a single command: npx skills add nutlope/hallmark. For Claude Code, the skill lands in ~/.claude/skills/hallmark/ and is auto-detected. For Cursor, the body of SKILL.md goes into .cursor/rules/hallmark.mdc (no frontmatter). For Codex and other agents, the repository can be cloned and the skill directory copied manually. Re-running the install command pulls the latest version.