CSS Crème

Answers two questions about a modern CSS feature with data instead of recall. First, its Baseline status (widely available, newly available, or limited availability), the date, and which core browsers lack it, read from the open web-features dataset at build time. Second, how many of CSS Crème's curated, decoded showcase sites ship it, which ones, how many of them guard it with @supports, and the exact @supports conditions they test. Also returns a fallback note where we have one, any name the feature has shipped under before (an agent that learned the old name will otherwise write it), and the documented limits that catch people out, each cited to the page it was read on. Call it before writing CSS that uses container queries, :has(), anchor positioning, @scope, view transitions, oklch(), color-mix(), light-dark(), subgrid, scroll-driven animations, @property, text-wrap and similar, so the CSS you write is accurate for today rather than for your training date. With no feature given it returns the Ship Gap: features that are safe and mostly ignored, and features that are early and shipped anyway.

Read a sample of pages from one site (from its sitemap.xml, or the homepage links when there is no sitemap) and report what is CONSISTENT across them: which declared tokens, colours, font stacks, radii and spacing values appear on every page read, and which appear on only some. One page shows what a page uses; a design system is a claim about consistency, and only a sample can test it. Returns counts and the pages actually read, never a score. Use when the user asks whether a site is really on a system, or wants the system rather than one page of it.

Fetch a public site's HTML and stylesheets and return what its CSS declares: named custom properties that look like design tokens, the colours it uses most, its font stacks, border radii, spacing values, and the framework it appears to be built with. Also returns a "drop" report: roughly how many words a web-to-markdown reader would carry away from this page, against the design decisions it would discard, because markdown is defined by throwing the design layer away. It reads CSS and does not render the page, so it reports a confidence ("tokens" when named properties were found, "derived" when only compiled CSS was available) and flags a JavaScript shell rather than pretending every site is equally legible. Use when the user wants to match a site that is not in the catalogue, or has fetched a page as markdown and needs what that markdown lost.

Return a short standing-instructions block that makes every future session read DESIGN.md before touching UI. Paste it whole into CLAUDE.md, AGENTS.md or .cursor/rules/design.mdc. It points at the DESIGN.md rather than restating it, and carries the token fingerprint so drift is detectable.

Fetch the full DESIGN.md for one theme: semantic colour roles, the complete shadcn token set in light and dark, typography, radius, spacing, MEASURED WCAG contrast ratios, and numbered rules the generated UI must follow. Read this before writing any UI. Save it at the repo root as DESIGN.md so it applies to every session.

Read the stylesheets of a public site and return a full DESIGN.md: semantic roles with the token each came from, measured WCAG contrast pairs, the tokens the site itself declares (framework internals counted separately), font families, the type scale with the ratio between steps, colour frequency, gradients, corner radii, spacing, an elevation ladder of shadows, breakpoints, the z-index ladder, interaction-state rule counts, motion, and whether a dark theme is declared. This is the artefact to hand a coding agent before it writes UI that should match a site. It reads declared CSS and does not execute JavaScript, so it reports what the stylesheets say rather than what the page renders.

Return the exact `npx shadcn@latest add <url>` command that installs one theme into a shadcn/ui project, plus the registry URL it reads. Use when the user says "install it" and you already know the id.

Get the shadcn/ui registry item (OKLCH tokens, light and dark) plus the paste-ready CSS variables for one theme, and the one-line command that installs it for real. Use after get_design_md when you are ready to write the tokens into globals.css.

Explains where a DESIGN.md belongs for a given coding agent (Claude Code, Cursor, v0, Codex, Lovable) so the design rules apply to every session rather than one message.

Browse the full catalogue of curated themes and templates. Use when the user wants to see options rather than search for one.

Find a design system by describing what you are building ("dark developer tool", "calm fintech dashboard", "playful consumer app"). Returns matching themes with their DESIGN.md URL and shadcn install command. Call this first when the user has no design system defined.

Every DESIGN.md carries a Fingerprint line. Pass the id and that fingerprint; the server answers whether the copy matches the current token set, and if not, returns the current tokens so the agent can update the file instead of following a stale one. Call this at the start of a session when a DESIGN.md is already in the repo.