HTML Coder Skill
Expert skill for professional HTML development with focus on semantic markup, accessibility, HTML5 features, and standards-compliant web content.
When to Use This Skill
- Creating HTML documents with semantic structure
- Building accessible forms with HTML5 validation
- Implementing responsive markup and multimedia
- Using HTML5 APIs (Canvas, SVG, Storage, Geolocation)
- Troubleshooting validation or accessibility issues
Core Capabilities
- Semantic HTML: Document structure, content sections, accessibility-first markup
- Forms: All input types, validation attributes, fieldsets, labels
- Media: Responsive images, audio/video, Canvas, SVG
- HTML5 APIs: Web Storage, Geolocation, Drag & Drop, Web Workers
- Accessibility: ARIA, screen reader support, WCAG compliance
Essential References
Core documentation for HTML experts:
references/add-css-style.md - Add CSS via link tag, inline, or embedded in htmlreferences/add-javascript.md - Add JavaScript via script src="link.js" tag, inline script, or embedded in htmlreferences/attributes.md - HTML attribute essentialsreferences/essentials.md - Semantic markup, validation, responsive techniquesreferences/global-attributes.md - Complete global attribute informationreferences/glossary.md - Complete HTML element and attribute referencereferences/standards.md - HTML5 specifications and standards
Best Practices
Semantic HTML - Use elements that convey meaning: <article>, <nav>, <header>, <section>, <footer>, not div soup.
Accessibility First - Proper heading hierarchy, alt text, labels with inputs, keyboard navigation, ARIA when needed.
HTML5 Validation - Leverage built-in validation (required, pattern, type="email") before JavaScript.
Responsive Images - Use <picture>, srcset, and loading="lazy" for performance.
Performance - Minimize DOM depth, optimize images, defer non-critical scripts, use semantic elements.
Quick Patterns
Semantic Page Structure
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Page Title</title>
</head>
<body>
<header><nav><!-- Navigation --></nav></header>
<main><article><!-- Content --></article></main>
<aside><!-- Sidebar --></aside>
<footer><!-- Footer --></footer>
</body>
</html>
Accessible Form
<form method="post" action="/submit">
<fieldset>
<legend>Contact</legend>
<label for="email">Email:</label>
<input type="email" id="email" name="email" required
pattern="[a-z0-9._%+-]+@[a-z0-9.-]+\.[a-z]{2,}$">
<button type="submit">Send</button>
</fieldset>
</form>
Responsive Image
<picture>
<source media="(min-width: 1200px)" srcset="large.webp">
<source media="(min-width: 768px)" srcset="medium.webp">
<img src="small.jpg" alt="Description" loading="lazy">
</picture>
Troubleshooting
- Validation: W3C Validator (validator.w3.org), check unclosed tags, verify nesting
- Accessibility: Lighthouse audit, screen reader testing, keyboard nav, color contrast
- Compatibility: Can I Use (caniuse.com), feature detection, provide fallbacks
Key Standards
1---2name: html-coder3description: Expert HTML development skill for building web pages, forms, and interactive content. Use when creating HTML documents, structuring web content, implementing semantic markup, adding forms and media, working with HTML5 APIs, or needing HTML templates, best practices, and accessibility guidance. Supports modern HTML5 standards and responsive design patterns.4---56# HTML Coder Skill78Expert skill for professional HTML development with focus on semantic markup, accessibility, HTML5 features, and standards-compliant web content.910## When to Use This Skill1112- Creating HTML documents with semantic structure13- Building accessible forms with HTML5 validation14- Implementing responsive markup and multimedia15- Using HTML5 APIs (Canvas, SVG, Storage, Geolocation)16- Troubleshooting validation or accessibility issues1718## Core Capabilities1920- **Semantic HTML**: Document structure, content sections, accessibility-first markup21- **Forms**: All input types, validation attributes, fieldsets, labels22- **Media**: Responsive images, audio/video, Canvas, SVG23- **HTML5 APIs**: Web Storage, Geolocation, Drag & Drop, Web Workers24- **Accessibility**: ARIA, screen reader support, WCAG compliance2526## Essential References2728Core documentation for HTML experts:2930- [`references/add-css-style.md`](references/add-css-style.md) - Add CSS via `link` tag, inline, or embedded in html31- [`references/add-javascript.md`](references/add-javascript.md) - Add JavaScript via `script src="link.js"` tag, inline `script`, or embedded in html32- [`references/attributes.md`](references/attributes.md) - HTML attribute essentials33- [`references/essentials.md`](references/essentials.md) - Semantic markup, validation, responsive techniques34- [`references/global-attributes.md`](references/global-attributes.md) - Complete global attribute information35- [`references/glossary.md`](references/glossary.md) - Complete HTML element and attribute reference36- [`references/standards.md`](references/standards.md) - HTML5 specifications and standards3738## Best Practices3940**Semantic HTML** - Use elements that convey meaning: `<article>`, `<nav>`, `<header>`, `<section>`, `<footer>`, not div soup.4142**Accessibility First** - Proper heading hierarchy, alt text, labels with inputs, keyboard navigation, ARIA when needed.4344**HTML5 Validation** - Leverage built-in validation (`required`, `pattern`, `type="email"`) before JavaScript.4546**Responsive Images** - Use `<picture>`, srcset, and `loading="lazy"` for performance.4748**Performance** - Minimize DOM depth, optimize images, defer non-critical scripts, use semantic elements.4950## Quick Patterns5152### Semantic Page Structure53```html54<!DOCTYPE html>55<html lang="en">56<head>57 <meta charset="UTF-8">58 <meta name="viewport" content="width=device-width, initial-scale=1.0">59 <title>Page Title</title>60</head>61<body>62 <header><nav><!-- Navigation --></nav></header>63 <main><article><!-- Content --></article></main>64 <aside><!-- Sidebar --></aside>65 <footer><!-- Footer --></footer>66</body>67</html>68```6970### Accessible Form71```html72<form method="post" action="/submit">73 <fieldset>74 <legend>Contact</legend>75 <label for="email">Email:</label>76 <input type="email" id="email" name="email" required77 pattern="[a-z0-9._%+-]+@[a-z0-9.-]+\.[a-z]{2,}$">78 <button type="submit">Send</button>79 </fieldset>80</form>81```8283### Responsive Image84```html85<picture>86 <source media="(min-width: 1200px)" srcset="large.webp">87 <source media="(min-width: 768px)" srcset="medium.webp">88 <img src="small.jpg" alt="Description" loading="lazy">89</picture>90```9192## Troubleshooting9394- **Validation**: W3C Validator (validator.w3.org), check unclosed tags, verify nesting95- **Accessibility**: Lighthouse audit, screen reader testing, keyboard nav, color contrast96- **Compatibility**: Can I Use (caniuse.com), feature detection, provide fallbacks9798## Key Standards99100- **WHATWG HTML Living Standard**: https://html.spec.whatwg.org/101- **WCAG Accessibility**: https://www.w3.org/WAI/WCAG21/quickref/102- **MDN Web Docs**: https://developer.mozilla.org/en-US/docs/Web/HTML103104---
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