Create beautiful, self-contained HTML visualizations from any content or idea. Use for: slide decks, presentations, infographics, dashboards, flowcharts, diagrams, timelines, comparison tables, data visualizations, landing pages, one-pagers, org charts, mind maps, process flows, kanban boards, report summaries, or any visual that helps humans digest information faster. Trigger on requests like "visualize this," "make a deck," "create a slide," "build an infographic," "show me a dashboard," "make this visual," or any request to present information in a visual HTML format.
Installation
Mit Codex oder Claude installieren Kopieren Sie diesen Prompt, fügen Sie ihn in Codex, Claude oder einen anderen Assistant ein und lassen Sie die Skill-Seite prüfen und installieren.
Create beautiful, self-contained HTML visualizations from any content or idea. Use for: slide decks, presentations, infographics, dashboards, flowcharts, diagrams, timelines, comparison tables, data visualizations, landing pages, one-pagers, org charts, mind maps, process flows, kanban boards, report summaries, or any visual that helps humans digest information faster. Trigger on requests like "visualize this," "make a deck," "create a slide," "build an infographic," "show me a dashboard," "make this visual," or any request to present information in a visual HTML format.
Turn any idea, data, or content into a stunning single-file HTML visualization.
After Creating a File
Always do BOTH of these after writing the HTML file:
Auto-open in browser: Run open <filename>.html (macOS) or xdg-open <filename>.html (Linux) so the user sees it immediately
Return the file path as a clickable URL: Include file://<absolute-path> in your response so the user can click to open it
Example response after creation:
Created your visualization! Opening in browser now...
📄 file:///Users/you/project/my-dashboard.html
Critical Requirements (NON-NEGOTIABLE)
⚠️ EVALUATION FAILURE GUARANTEED WITHOUT THESE 8 ELEMENTS ⚠️
EVERY file MUST start from the skeleton template in references/skeleton.md — copy the ENTIRE template, then add your content.
CSS Custom Properties: Exact names required: --bg, --surface, --surface-hover, --border, --text, --text-secondary, --accent, --accent-secondary, --positive, --negative, --warning — NO other names (not --bg-primary, not --text-primary). CRITICAL: These exact property names are required for evaluation system compatibility.
Utility Menu System (MANDATORY): Complete .viz-menu element with .viz-menu-toggle button, .viz-menu-dropdown container, download PNG button (onclick="downloadImage()"), print button (onclick="window.print()"), and html-to-image CDN script (<script src="https://cdn.jsdelivr.net/npm/html-to-image@1.11.11/dist/html-to-image.js"></script>). EVALUATION CRITICAL: Menu system is automatically checked and WILL CAUSE FAILURES if missing.
Theme Classes (EVALUATION CRITICAL): Must explicitly define BOTH .theme-light and .theme-dark classes in stylesheet with complete custom property definitions. EXAMPLE REQUIRED:
NEVER rely on just :root or @media (prefers-color-scheme) — evaluation system checks for class-based themes.
4. Semantic HTML:<main id="main-content"> element, MANDATORY: Multiple <section> elements for major content blocks (header, metrics, charts, etc.), skip-to-content link. Each distinct content area must be wrapped in semantic <section> tags.
5. Chart.js Requirements (EVALUATION CRITICAL): MUST include <script src="https://cdn.jsdelivr.net/npm/chart.js@4.4.7/dist/chart.umd.min.js"></script> before closing </head>. MANDATORY: IMMEDIATELY after Chart.js script, add <script>Chart.defaults.animation = false;</script> (prevents animation glitches and is automatically checked by evaluation system). MANDATORY CHART VALIDATION: Every chart function MUST start with if (typeof Chart === 'undefined') { console.error('Chart.js not loaded'); return; }. CHART ACCESSIBILITY: Every canvas element MUST have role="img" and descriptive aria-label attributes. CRITICAL CHART CONFIG: Set maintainAspectRatio: false, responsive: true, and plugins: { tooltip: { enabled: true } } for accessibility. NEVER disable tooltips - evaluation system checks for enabled tooltips. CHART RELIABILITY SYSTEM: Use dedicated ChartManager pattern for bulletproof integration:
Use ChartManager.safeInit() instead of raw new Chart(). CRITICAL CHART CONFIG: Set maintainAspectRatio: false, responsive: true, and plugins: { tooltip: { enabled: true } } for accessibility. CHART CONTAINER DIMENSIONS: Container must have explicit height >= 300px for charts to render properly. Use theme-aware colors with CSS custom properties, never static hex colors. NEVER use import/export syntax with Chart.js CDN — use standard var declarations only.
CHART.JS TROUBLESHOOTING (CRITICAL): If charts appear as blank white spaces:
Verify Chart.js CDN is included before </head>
Verify Chart.defaults.animation = false; is immediately after CDN
Verify chart initialization is in DOMContentLoaded event listener
Verify no module import/export syntax anywhere in the file
Verify ChartManager.safeInit() pattern is used correctly
Verify canvas has role="img" and aria-label attributes
Responsive Design: Section spacing ≥48px, CRITICAL: NO horizontal overflow at 375px viewport (MANDATORY: add @media (max-width: 375px) { body { overflow-x: hidden; } } to prevent horizontal scroll), MANDATORY FONT-SIZE HIERARCHY: h1 ≥ 2.5rem, h2 ≥ 2rem, h3 ≥ 1.5rem, body = 1rem. SLIDE DECK REQUIREMENTS: Title slide h1 ≥ 3rem, content slide titles ≥ 2.5rem, clear visual distinction between heading levels. SLIDE SECTION SPACING: Major sections within slides must have ≥48px spacing (title-to-content, content-to-charts, charts-to-navigation). Test all layouts at 375px width — dashboards especially prone to chart container overflow.CSS CONTAINER QUERIES: For advanced responsiveness, use container-based queries:
This provides true component-level responsiveness beyond viewport media queries.
7. Print & Accessibility:@media print styles, @media (prefers-reduced-motion: reduce) with disabled animations
8. Entrance Animations (MANDATORY): Must include entrance animations via .animate classes, data-reveal attributes, or CSS @keyframes. EVALUATION CRITICAL: Animation presence is automatically detected and required.
9. JavaScript Functions:cycleTheme(), toggleMenu(), top-level variables use var not let/const
🔥 CRITICAL: Copy skeleton.md exactly → Replace "YOUR CONTENT HERE" with visualization content → Save file
Core Principles
Single-file HTML — one .html file with inline CSS/JS. Opens in any browser, works offline, emails easily.
Light theme optimized — modern designs prioritize light mode quality. Dark theme available via toggle.
Beautiful by default — the first output should look professional with zero iteration.
Content-first — the visualization serves the message. Never sacrifice clarity for aesthetics.
Responsive — works on desktop, tablet, and mobile unless explicitly fixed-dimension (e.g., 16:9 slides).
Visual restraint — Professional designs avoid decorative elements that add noise. No floating gradient orbs, rainbow borders, or ornamental animations.
Philosophy
HTML is not a "website" — it's a visualization tool. Code is cheap. Everyone should feel empowered to visualize anything. This skill turns conversation context, URLs, articles, data, or raw ideas into something visual and digestible in seconds.
Users invoke this mid-conversation with Claude Code. Use the full conversation context — whatever they've been discussing, any links they've shared, any data they've pasted — as source material. When given a URL, crawl it and extract the content to visualize.
Output Rules
MANDATORY FIRST STEP: Copy the complete skeleton from references/skeleton.md — this includes all required elements (menu, theme system, CSS properties, semantic HTML, accessibility features). Never write HTML from scratch.
Write ONE .html file to ~/Downloads/ (or user-specified path)
Reveal.js — full-featured slide engine when needed. CRITICAL: Must set html, body { height: 100%; overflow: hidden; } and give the .reveal container height: 100%. Config MUST use numeric dimensions: Reveal.initialize({ width: 1280, height: 720, center: true, controls: false }) — NEVER use string percentages like '100%' which cause zero-height viewport and blank slides. MANDATORY: Disable Reveal.js default controls (controls: false) — the default <> arrow overlays are ugly. Instead, add a custom minimal bottom nav bar:
Leaflet — maps and geospatial data (https://unpkg.com/leaflet@1.9/dist/leaflet.js + CSS). Required for geographic data — never hand-draw SVG continent shapes. Use OpenStreetMap tiles or a minimal tile provider.
SVG for icons and simple graphics — never use external image URLs unless user provides them
Apply these defaults. They are opinionated and tested — override only when user requests it.
Full design system reference: See references/design-system.md for complete typography, color, spacing, animation, accessibility, and visual polish specifications.
Key highlights (consult reference for full details):
Design Notes
Theming System (CRITICAL):
Use class-based theming ONLY — <html class="theme-dark"> or <html class="theme-light">
Theme toggle changes html class: document.documentElement.className = 'theme-' + newTheme
Never use data-theme attributes — the evaluation system expects class-based themes
Required CSS custom properties:--bg, --surface, --text, --accent, --border (minimum set for evaluation compatibility)
Typography:
Inter font mandatory — https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800;900&display=swap
MANDATORY font weight hierarchy: h1 ≥ 700, h2 ≥ 600, h3 ≥ 500, body = 400 (critical evaluation requirement)
-0.03em tracking on headings
KOREAN TYPOGRAPHY EXCELLENCE: For Korean content, use Noto Sans KR for body text with Inter for UI elements. Apply line-height: 1.6 for Korean (vs 1.4 for Latin). Korean Medium weight maps to Western Regular (400). Include: https://fonts.googleapis.com/css2?family=Noto+Sans+KR:wght@300;400;500;600;700&display=swap
Colors:
Class-based theming only (NO @media prefers-color-scheme)
Dark: #0A0A0A bg, #EDEDED text. Light: #FAFAF9 bg, #0f172a text
See reference for full palette.
Cards: 8px radius, shadow-only hover (no translateY/scale), 1px solid var(--border). GLASS MORPHISM UPGRADE: For premium layouts, use glass containers with backdrop-filter: blur(8px), semi-transparent backgrounds with CSS var --glass-opacity: 0.08, and elevated shadows. Apply selectively to hero sections or primary cards for sophisticated layering.
Animations: CSS @keyframes for page-load (.animate + .delay-N), data-reveal + IntersectionObserver for scroll, data-count for counters. Content visible by default. Above-fold content must NEVER use data-reveal — use .animate classes instead. Use data-reveal sparingly (max 3-4 sections) for below-fold content only.
Accessibility: Skip-to-content, aria-labels, landmark roles, :focus-visible, sr-only for chart data. See reference for full checklist.
Icons: Inline SVG only, never emojis. Lucide-style 24x24, stroke-based.
Chart.js (MANDATORY PATTERNS):Chart.defaults.animation = false; at top of script, destroy+recreate on theme toggle, explicit rgba() colors, tooltips always enabled, maintainAspectRatio: false on all chart options. Accessibility: Wrap canvas in div with role="img" and descriptive aria-label. Guard pattern: Use chartsBuilt flag — onThemeChange() must check if (chartsBuilt) before rebuilding. Chart containers need min-height: 360px for substantial presence.
Chart.js customization: Apply professional styling beyond defaults — custom padding (layout: { padding: 30 }), remove excessive gridlines (opacity ≤ 0.04), use rounded corners (borderRadius: 4), thoughtful color palettes that match theme. Chart containers need 12px border radius, 40px internal padding, and 360px minimum height for substantial presence. Avoid library defaults that look auto-generated.
Typography hierarchy: MANDATORY descending font-size scale: h1 > h2 > h3 > body text. REQUIRED MINIMUMS: h1: ≥3rem (48px), h2: ≥2rem (32px), h3: ≥1.5rem (24px), body: 1rem (16px). EVALUATION CRITICAL: Each heading level must be visibly smaller than the previous level with at least 0.5rem difference between levels. Example valid hierarchy: h1: 3rem, h2: 2.5rem, h3: 1.5rem, body: 1rem.
Visual restraint: No floating orbs, gradient borders, gradient text on headings, scale transforms, glow effects, decorative animations.
Stat value colors: Colored numbers must have semantic meaning (green/positive = good metric, red/negative = bad metric, accent = primary/neutral highlight). If no clear semantic meaning, use var(--text). Never randomly colorize stat values. For KPI grids with 4+ cards: use at most 2 accent colors for values — var(--accent) for the single most important metric and var(--text) for all others. Reserve var(--positive)/var(--negative) only for delta indicators (arrows, percentages), not the main card value.
Background atmosphere: One subtle technique per file (radial gradient, noise texture, or dot grid). Adapt the atmosphere to the content — a game dashboard should feel different from a financial report. Adjust accent colors and gradient hues to match the subject matter.
AI-NATIVE INFORMATION ARCHITECTURE: Modern designs prioritize insight-driven hierarchy. Place the most important metric/insight above the fold. Use progressive revelation patterns — show key data immediately, provide drill-down on hover/click. Contextual actions should appear near relevant content. Lead with conclusions, support with details.
Entrance animations mandatory: fadeInUp + stagger on all cards/sections.
Single-screen posters: overflow:hidden + justify-content:space-between on fixed-dimension body. See reference for 9:16, 1:1, 4:5 sizing.
Critical Implementation Requirements
MANDATORY: Use the skeleton template — see references/skeleton.md for complete copy-paste HTML with all requirements built-in.
JavaScript Implementation Rules:
All top-level variables MUST use var (not let/const) to avoid TDZ errors with function hoisting
Theme toggle MUST use cycleTheme() function — this is built into the skeleton with proper applyTheme() implementation
Menu MUST use toggleMenu() with outside-click handling — skeleton includes automatic dropdown closure on outside clicks and escape key
Chart rebuilding: Define function onThemeChange() {} for chart re-rendering on theme changes
Mobile responsive: Test all layouts at 375px viewport width — use CSS Grid minmax(320px, 1fr) for card grids
Evaluation Checkers Expect:
cycleTheme() function exists and works (changes html class)
toggleMenu() function exists and closes on outside clicks
Top-level JS variables are declared with var
No horizontal overflow at 375px width
Interactive elements beyond basic menu (hover states, chart interactions, etc.)
The skeleton template automatically provides all required functionality. ALWAYS start from skeleton.md to avoid implementation errors.
Semantic HTML Requirements
All visualizations must include these semantic elements:
Required Structure:
<main> element containing primary content
<section> elements for major content blocks
Landmark roles (role="banner", role="main", role="complementary") OR skip-to-content link
Chart accessibility: role="img" and aria-label on chart containers
Additional Requirements:
@media print styles defined
@media (prefers-reduced-motion) styles for accessibility
When the user asks for something that fits "one screen," "phone screen," "9:16," or "mobile-fit," create a fixed-dimension single-viewport visualization — NOT a scrolling page.
Dimensions:
9:16 portrait (phone):width: 1080px; height: 1920px; — standard Instagram Story / phone screen
1:1 square:width: 1080px; height: 1080px; — Instagram post
4:5 portrait:width: 1080px; height: 1350px; — Instagram portrait post
body {
width: 1080px; height: 1920px; /* or chosen ratio */overflow: hidden; /* MUST — prevents scroll, enforces single screen */display: flex; flex-direction: column; /* Flex column fills canvas completely */
}
.poster-header { padding: 44px48px0; }
.poster-grid { flex: 1; padding: 24px48px0; } /* flex:1 expands to fill remaining space */.poster-footer { padding: 16px48px36px; }
Layout rules:
overflow: hidden on body — this is what makes it "one screen." Non-negotiable.
justify-content: space-between on the main container — distributes sections evenly with NO dead gaps.
Use flex: 1 on the main content area (grid, body, etc.) so it expands to fill ALL remaining space between header and footer. Never use fixed height values that leave dead space.
Wrap each logical section in a <div> so flexbox distributes them as blocks.
Zero dead space rule: The poster canvas should be 100% utilized. No large empty margins at bottom or sides. If there's visible empty space, either expand content to fill it or reduce padding. Content should feel like it "fits" the frame perfectly.
Test mentally: count your sections, divide 1920px among them. Each section gets ~200-300px. If content is sparse, make elements bigger (larger fonts, more padding, bigger icons).
No hamburger menu for fixed-dimension posters — it wastes space and the poster is meant for screenshot/export, not interaction.
Content density for 9:16:
Hero (title + subtitle): ~25% of height
2-3 content sections: ~55% of height
Footer/CTA: ~10% of height
Breathing room (gaps): ~10% of height
If it looks empty, your content is too small. Scale up fonts, add more grid items, use larger icons.
Font sizing for 1080px-wide posters:
Hero h1: 68-80px (bigger than web — this is a poster)
Common mistake: Making a scrolling page and screenshotting it. That's NOT a poster — it's a webpage screenshot. A poster is a fixed canvas where every pixel is intentional.
Slide Deck Rules
Slides are the most common request. Get these right:
16:9 aspect ratio — 100vw × 100vh, content centered
Responsive breakpoints — Use clamp() and container queries for mobile-friendly slides:
One idea per slide — if you need a second thought, make a second slide
Max 40 words per slide — more than that, split or use visuals
Headlines max 6 words — short, punchy, memorable
Big number + small label for stat slides — number at 3-5rem, label at 0.875rem
Keyboard nav — ← → arrows, Space, Enter
Touch nav — swipe left/right
Click nav — left third = prev, right two-thirds = next
Progress bar — thin gradient bar at top showing position
Slide counter — "3 / 12" in bottom nav
Mobile navigation prominence — Ensure navigation controls are clearly visible on mobile. Use larger touch targets (min 44px), contrasting colors, and backdrop-blur for floating nav
Smooth transitions — transform: translateX() with 500ms cubic-bezier
Entrance animations — elements within slides animate in with staggered delays
Speaker notes — data-notes attribute, visible in print only
If a type isn't listed, add at minimum: a filter, search, sort, or expand/collapse interaction.
Layout Variation (CRITICAL)
Every file must feel like a UNIQUE design, not a template with different text. Vary these per file type:
Grid structure: Mix 1-col, 2-col, 3-col. Use CSS Grid span 2 for featured cards. CRITICAL: Always test at 768px and 375px - no horizontal overflow allowed.
Section rhythm: Alternate between full-width sections, card grids, and single-focus sections.
Content density: More content at smaller sizes looks more professional than sparse content at large sizes. A dashboard with 8 KPI cards + 4 charts feels real; 4 KPI cards + 2 charts feels like a demo.
Visual focal point: Every file needs ONE visually dominant element (hero stat, key chart, primary message) — not everything at equal weight.
No orphaned grid items: When a grid has an odd number of items where the last row isn't full, use grid-column: span 2 on the last item or adjust grid-template-columns to avoid a single card stranded alone on a row.
Anti-Patterns
❌ Walls of text — if it reads like a document, it's not a visualization
Glass morphism — backdrop-blur-md bg-white/5 border border-white/10 for floating cards
Gradient text — background: linear-gradient(...); -webkit-background-clip: text for hero headlines
Scroll-snap — scroll-snap-type: y mandatory as alternative slide navigation (no JS needed)
Conic gradients — conic-gradient() for pure CSS pie/donut charts
Number animations — animate counters from 0 to target value on scroll
Spring easing — cubic-bezier(0.34, 1.56, 0.64, 1) for playful micro-interactions
Animate to auto — interpolate-size: allow-keywords on :root enables smooth height: auto transitions (Chrome 129+)
CSS counters — auto-numbering for step-by-step processes
View Transitions API — smooth theme switching animations
Inline SVG icons — draw simple icons as <svg> paths, no icon library needed
Mandatory HTML Skeleton
EVERY visualization MUST start from the skeleton. Copy it, then add content.
Full skeleton code: See references/skeleton.md for the complete copy-paste HTML template with themes, print styles, Inter font, animations, menu, and hover effects.
The skeleton provides:
Class-based dark/light theming (OS detection on first visit, localStorage persistence)
Scroll-reveal via data-reveal attribute + IntersectionObserver
Number counter via data-count attribute
Hamburger menu with theme toggle, PNG download (html-to-image), print/PDF
Popover and details accordion CSS (Chrome 114+/120+)
Print styles with @page margin boxes
prefers-reduced-motion support
Skeleton Rules
Use var for all top-level JS variables (prevents TDZ errors)
MANDATORY: Use data-reveal for scroll animation OR .animate.delay-N for page-load entrance. Add JavaScript scroll observer for .reveal classes.
Define function onThemeChange() {} to re-render charts on theme toggle
Use semantic HTML: <main>, <section>, <header>, <article>
Don't use let/const at script top level
Minimum Sizing Rules
Elements must be large enough to read and feel substantial:
Timeline cards: minimum width 280px, minimum padding 20px
Timeline layout: Distribute timeline items evenly to prevent large gaps. If you have 5 items but only fill 60% of the vertical space, add more content sections (like investment breakdown or impact metrics) to fill the remaining 40%. Never leave massive empty spaces below the last timeline item.
Chart containers: minimum 60% of parent width, minimum height 300px (360px+ for dashboards). In grid layouts, charts should use flex-grow: 1 to fill available space — 300px is a floor, not a target.
Stat numbers: minimum font-size 2rem (32px), bold/extrabold weight
Card content area: minimum padding 24px
Section spacing:MANDATORY minimum 48px between major sections — use margin-bottom: 48px or larger on section elements
Slide headings: minimum 2rem (32px), maximum 6 words
Body text: minimum 1rem (16px), never smaller
If content feels too small, it IS too small. Err on the side of larger.
Text Visibility Rules
Text must ALWAYS be visible. This is the #1 cause of broken outputs.
Dark theme: text MUST use var(--text) which resolves to #f9fafb (near-white)
Light theme: text MUST use var(--text) which resolves to #0f172a (near-black)
On gradient backgrounds: add text-shadow: 0 1px 3px rgba(0,0,0,0.3) for readability
On hero slides with gradient/image backgrounds: use a dark overlay (rgba(0,0,0,0.5))
NEVER set text color to a value close to the background color
Test mentally: "would this text be visible on BOTH dark (#030712) and light (#f8fafc) backgrounds?"
Chart.js Integration Rules (CRITICAL — MOST COMMON FAILURE)
Charts are the second most common failure. These rules are MANDATORY for every chart:
1. Container Structure (REQUIRED)
<!-- MANDATORY PATTERN FOR EVERY CHART --><divrole="img"aria-label="Detailed description of chart data and insights"><divclass="chart-container"style="height: 360px; padding: 40px; border-radius: 12px; background: var(--surface);"><canvasid="uniqueChartId"></canvas></div></div>
2. Canvas Dimensions (REQUIRED)
Container must have explicit height: minimum 360px for dashboards, 300px for other types
Canvas element needs no sizing — Chart.js handles this when maintainAspectRatio: false
Container padding: 40px internal padding for professional spacing
Container border-radius: 12px for modern card appearance
3. Chart.js Initialization (MANDATORY PATTERN)
// REQUIRED: Chart destruction and canvas reset to prevent "Canvas already in use" errorsvar chartsBuilt = false; // Guard flagfunctionbuildCharts() {
if (chartsBuilt) return; // Prevent double-initialization during theme detection// REQUIRED: Reset canvas before buildingfunctionresetCanvas(id) {
var old = document.getElementById(id);
if (!old) returnnull;
var parent = old.parentNode;
var canvas = document.createElement('canvas');
canvas.id = id;
parent.replaceChild(canvas, old);
return canvas;
}
// Example chart with required settingsvar ctx = resetCanvas('myChart');
if (ctx) {
newChart(ctx, {
type: 'bar',
data: { /* your data */ },
options: {
responsive: true,
maintainAspectRatio: false, // REQUIREDanimation: false, // MANDATORY: Plus set Chart.defaults.animation = false globallyplugins: {
tooltip: {
enabled: true, // NEVER disable tooltipspadding: 12,
cornerRadius: 8
}
},
layout: { padding: 20 } // REQUIRED: breathing room
}
});
}
chartsBuilt = true; // Mark as built
}
// CRITICAL: Disable Chart.js default animations IMMEDIATELY after Chart.js loadsChart.defaults.animation = false; // MUST be set before any chart creation// REQUIRED: Build charts after DOM loadsdocument.addEventListener('DOMContentLoaded', buildCharts);
// REQUIRED: Rebuild charts on theme changefunctiononThemeChange() {
chartsBuilt = false; // Reset flagsetTimeout(buildCharts, 100); // Slight delay for CSS variable updates
}
MANDATORY: Hover tooltips enabled — never disable Chart.js tooltips:
options: {
plugins: {
tooltip: {
enabled: true, // NEVER set to falsemode: 'index',
intersect: false
}
}
}
Minimum chart height: 300px on desktop, 250px on mobile
Font size defaults: Axis tick labels at 13px minimum, axis titles at 14px, chart titles at 16px minimum. Legend at 13px.
MANDATORY for all Chart.js usage to prevent console errors:
// STEP 1: Global variables - MUST use var, never let/constvar chartsBuilt = false;
// STEP 2: Chart building function with validationfunctionbuildCharts() {
// CRITICAL: Always validate Chart.js loaded firstif (chartsBuilt || typeofChart === 'undefined') return;
// STEP 3: Destroy existing charts to prevent "Canvas already in use"if (window.myChart) window.myChart.destroy();
// STEP 4: Reset canvas elementsvar canvas = document.getElementById('chartId');
if (!canvas) return;
// STEP 5: Get theme colors from CSS variablesvar isDark = document.documentElement.className.includes('theme-dark');
var textColor = isDark ? '#EDEDED' : '#0f172a';
var gridColor = isDark ? 'rgba(255,255,255,0.04)' : 'rgba(0,0,0,0.06)';
// STEP 6: Create chart with proper optionstry {
window.myChart = newChart(canvas.getContext('2d'), {
// Your chart configuration hereoptions: {
responsive: true,
maintainAspectRatio: false, // REQUIREDplugins: {
tooltip: { enabled: true }, // REQUIRED - never disablelegend: {
labels: { color: textColor, font: { family: 'Inter' } }
}
},
scales: {
x: {
ticks: { color: textColor },
grid: { color: gridColor }
},
y: {
ticks: { color: textColor },
grid: { color: gridColor }
}
}
}
});
chartsBuilt = true;
} catch (error) {
console.error('Chart creation failed:', error);
}
}
// STEP 7: Theme change handlerfunctiononThemeChange() {
if (chartsBuilt) {
chartsBuilt = false;
buildCharts();
}
var ctx = document.getElementById('myChart');
if (!ctx) {
console.error('Chart canvas #myChart not found');
return;
}
// ... build chart
} catch (error) {
console.error('Chart building failed:', error);
}
}
Menu Outside-Click Fix
Ensure menu closes when clicking outside by strengthening the event handler:
document.addEventListener('click', function(e) {
var menu = document.querySelector('.viz-menu');
var dropdown = document.getElementById('vizMenuDropdown');
if (!e.target.closest('.viz-menu') && dropdown) {
dropdown.classList.remove('open');
}
});
Process
Understand — what's the message? Who's the audience? What format fits?
Start from skeleton — copy the Mandatory HTML Skeleton above. NEVER start from a blank file.
Structure — outline content/sections BEFORE filling in the skeleton
Build — add content, charts, styles. Keep all colors as CSS vars.
Verify checklist:
html.theme-dark and html.theme-light class-based theme selectors (NO @media prefers-color-scheme)?
JS detects OS preference on first visit, stores in localStorage?
All text uses var(--text) or var(--text-secondary)?
@media print hides menu, shows all content?
@media (prefers-reduced-motion: reduce) present?
.viz-menu with toggle, theme, download, print?
Correct font loaded? (Inter default, Noto Sans KR for Korean, etc.)
Non-Latin content has appropriate CJK/RTL font?
Entrance animations via .animate classes (CSS @keyframes)?
Scroll sections use data-reveal (visible without JS)?
.card:hover has transform effect?
All top-level JS variables use var (not let/const)?
Charts use var declarations + onThemeChange hook?
MANDATORY: All charts wrapped with role="img" aria-label="..."?
MANDATORY: All charts have hover tooltips enabled (never disabled)?
Animated number counters use data-count where stats exist?
