Design system and guidelines for Claude's built-in generative UI — the show_widget tool that renders interactive HTML/SVG widgets inline in claude.ai conversations. This skill provides the complete Anthropic "Imagine" design system so Claude produces high-quality widgets without needing to call read

Generative UI Skill This skill contains the complete design system for Claude's built in show widget tool — the generative UI feature that renders interactive HTML/SVG widgets inline in claude.ai conversations. The guidelines below are the actual Anthropic "Imagine — Visual Creation Suite" design rules, extracted so you can produce high quality widgets directly without needing the read me setup call. How it works : On claude.ai, Claude has access to the show widget tool which renders raw HTML/SVG fragments inline in the conversation. This skill provides the design system, templates, and patterns to use it well. Codex and other hosts : First check the available tools. Use the host's documented visualization interface when provided; otherwise save a complete HTML document in the workspace and return a clickable file link. For standalone output, the fragment only rule below does not apply: include a document wrapper and viewport metadata, define the CSS variables and SVG classes used by the templates (including dark mode colors), and load chart dependencies explicitly. The host specific CDN allowlist and injected styles below describe Claude's renderer; they are not Codex capabilities. Remove chat follow up buttons and sendPrompt handlers when that bridge is unavailable; keep local sliders and calculations functional. Verify the saved output in a browser when available. Step 1: Pick the Right Visual Type Route on the verb , not the noun. Same subject, different visual depending on what was asked: User says Type Format "how does X work" Illustrative diagram SVG "X architecture" Structural diagram SVG "what are the steps" Flowchart SVG "explain compound interest" Interactive explainer HTML "compare these options" Comparison grid HTML "show revenue chart" Chart.js chart HTML "create a contact card" Data record HTML "draw a sunset" Art/illustration SVG Step 2: Build the Widget Structure (strict order) Output streams token by token. Styles must exist before the elements they target, and scripts must run after the DOM is ready. Philosophy Seamless : Users shouldn't notice where the host UI ends and your widget begins Flat : No gradients, mesh backgrounds, noise textures, or decorative effects. Clean flat surfaces Compact : Show the essential inline. Explain the rest in text No stock "AI design" defaults : skip cream or off white panels, italic accent words in headings, numbered "01 / 02 / 03" section labels, monospace labels outside code, and pill shaped buttons — they read as generic and clash with the host UI Text goes in your response, visuals go in the tool — write explanatory text, descriptions, and summaries as normal response text outside the tool call; the widget holds only the visual element Core Rules No <! comments or / comments / (waste tokens, break streaming) No font size below 11px No emoji — use CSS shapes or SVG paths No gradients, drop shadows, blur, glow, or neon effects No dark/colored backgrounds on outer containers (transparent only — host provides the bg) Typography : two weights only: 400 regular, 500 medium. Never use 600 or 700. Headings: h1=22px, h2=18px, h3=16px — all font weight 500. Body text=16px, weight 400, line height 1.7 Sentence case always. Never Title Case, never ALL CAPS No mid sentence bolding — entity names go in code style not bold No <!DOCTYPE , <html , <head , or <body — just content fragments No position: fixed — use normal flow layouts No tabs, carousels, or display: none sections during streaming No nested scrolling — auto fit height Corners: border radius: var( border radius lg) for cards, var( border radius md) for elements No rounded corners on single sided borders (border left, border top) Round every displayed number — use Math.round() , .toFixed(n) , or Intl.NumberFormat CDN Allowlist (CSP enforced) External resources may ONLY load from: cdnjs.cloudflare.com cdn.jsdelivr.net unpkg.com esm.sh All other origins are blocked — the request silently fails. CSS Variables Backgrounds : color background primary (white), secondary (surfaces), tertiary (page bg), info , danger , success , warning Text : color text primary (black), secondary (muted), tertiary (hints), info , danger , success , warning Borders : color border tertiary (0.15α, default), secondary (0.3α, hover), primary (0.4α), semantic info/ danger/ success/ warning Typography : font sans , font serif , font mono Layout : border radius md (8px), border radius lg (12px), border radius xl (16px) All auto adapt to light/dark mode. Dark mode is mandatory — every color must work in both modes: In HTML: always use CSS variables for text. Never hardcode colors like color: 333 In SVG: use pre built color classes ( c blue , c teal , etc.) — they handle light/dark automatically Mental test: if the background were near black, would every text element still be readable? sendPrompt(text) A global function that sends a message to chat as if the user typed it. Use it when the user's next step benefits from Claude thinking. Handle filtering, sorting, toggling, and calculations in JS instead. Step 3: Render with the Available Host When the host exposes show widget , pass your widget code directly as below. In Codex without that tool, follow the standalone HTML path above; do not invent a show widget call. Parameter Type Required Description title string Yes Snake case identifier for the widget widget code string Yes HTML or SVG code. For SVG: start with <svg . For HTML: content fragment For SVG output: start widget code with <svg — it will be auto detected and wrapped appropriately. Step 4: Chart.js Template For charts, use onload callback pattern to handle script load ordering: Chart.js rules: Canvas cannot resolve CSS variables — use hardcoded hex Set height ONLY on the wrapper div, never on canvas itself Always responsive: true, maintainAspectRatio: false Always disable default legend, build custom HTML legends Number formatting: $5M not $ 5M (negative sign before currency symbol) Use onload="initChart()" on CDN script tag + if (window.Chart) initChart(); as fallback Step 5: SVG Diagram Template For flowcharts and diagrams, use SVG with pre built classes: SVG rules: ViewBox always 680px wide ( viewBox="0 0 680 H" ). Set H to fit content + 40px padding Safe area: x=40 to x=640, y=40 to y=(H 40) Pre built classes: t (14px), ts (12px secondary), th (14px medium 500), box , node , arr , c {color} Every <text element must carry a class ( t , ts , or th ) Use dominant baseline="central" for vertical text centering in boxes Connector paths need fill="none" (SVG defaults to fill: black ) Stroke width: 0.5px for borders and edges Make all nodes clickable: onclick="sendPrompt('...')" Step 6: Interactive Explainer Template For interactive explainers (sliders, live calculations, inline SVG): Use sendPrompt() to let users ask follow ups: sendPrompt('What if I increase the rate to 10%?') Step 7: Respond to the User After rendering the widget, briefly explain: 1. What the widget shows 2. How to interact with it (which controls do what) 3. One key insight from the data Keep it concise — the widget speaks for itself. Reference Files references/design system.md — Complete color palette (9 ramps × 7 stops), CSS variables, UI component patterns, metric cards, layout rules references/svg and diagrams.md — SVG viewBox setup, font calibration, pre built classes, flowchart/structural/illustrative diagram patterns with examples references/chart js.md — Chart.js configuration, script load ordering, canvas sizing, legend patterns, dashboard layout Read the relevant reference file when you need specific design tokens, SVG coordinate math, or Chart.js configuration details.

generative-ui