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Validate HTML against W3C standards — measured AI agent skill | DecimalAI

thedaviddias/w3c-compliant

SkillScore95Maintained

Use when reviewing templates, rendered HTML, or shared components related to Validate HTML against W3C standards. Validate the final browser-facing markup, not just the source framework abstraction.

by thedaviddias

Links this skill to your agents and keeps it current with the author’s updates.

Automatic

Frontend / UI pack

decimalai skills pull thedaviddias-w3c-compliant

Get this skill — curl · raw file

curl -fsSL https://app.decimal.ai/s/thedaviddias-w3c-compliant/SKILL.md

Raw file: /s/thedaviddias-w3c-compliant/SKILL.md ↗ · machine-readable summary at /s/thedaviddias-w3c-compliant.json ↗

In productionGlobal

how this skill behaves on real traffic · last 30 days

No production data for this skill yet — usage numbers appear here once agents start running it.

Anonymized aggregate across every org using this skill — proof from real production use, not a demo.

Does this skill help? · Benchmark: with vs. withoutsign in to run this on your agents

22 test cases from the publisher’s eval.yaml · each run twice on gemini-3.6-flash — with the skill injected, then without · last run 6h ago

Yes — +5% lift+0% tokens0% turns95% of whole cases pass with skill (21/22)

Test case	Without → With	Effect	Δ tokens	Δ turns
case-08	✗→✓	▲ Improved	40%	0%
case-02	✓→✓	＝ Same ✓	7%	0%
case-03	✓→✓	＝ Same ✓	-23%	0%
case-04	✓→✓	＝ Same ✓	-26%	0%
case-05	✓→✓	＝ Same ✓	-9%	0%

Showing 5 of 22 cases

SkillSafety

✓ 3 of 3 passed

Code scan15 of 15 checks clean

0 critical · 0 warning · 0 info — scanner v4 — 8/3/2026

live_secretremote_code_executionreverse_shelldata_exfiltrationssrf_metadataagent_snoopinganti_refusaldestructive_commandsobfuscated_unicodeunicode_homoglyphopaque_blobsuspicious_urltool_overreachtrigger_abuseprompt_injection_phrasing

IntentSafe

LLM judge · does the skill do what it claims

ContentClean

LLM judge · policy & harmful-content review

Source

Imported

thedaviddias / front-end-checklist

skills/w3c-compliant/SKILL.md

View on GitHub ↗

Imported 8/3/2026Version v1Bundled 1 file

Skill contents

references/

SKILL.md

Validate HTML against W3C standards

Invalid HTML causes unpredictable rendering across browsers, breaks accessibility tools, and makes debugging significantly harder.

Quick Reference

Use validator.w3.org or browser extensions for validation
Fix errors first, then warnings (errors cause rendering issues)
Integrate validation into CI/CD with html-validate
Common issues: unclosed tags, invalid nesting, missing attributes

Check

Validate HTML markup using the W3C HTML Validator to identify and fix markup errors that could cause cross-browser compatibility issues.

Fix

Run HTML through W3C validator and fix reported errors including unclosed tags, missing attributes, and invalid nesting.

Explain

Explain why W3C HTML validation is important for cross-browser compatibility, accessibility, and maintainable code.

Code Review

Review templates, server-rendered HTML, and shared components that output markup related to Validate HTML against W3C standards. Flag exact elements, attributes, and routes where the rendered HTML violates the rule.

For full implementation details, code examples, and framework-specific guidance, see references/rule.md.

Rule page: https://frontendchecklist.io/en/rules/html/w3c-compliant

Want to see if thedaviddias/w3c-compliant would activate on your phrasing? Try it before you install — no LLM call, no signup.

Other measured skills in the registry, with their headline benchmark lift.