What is layout shift prevention and why does width/height matter?

Setting width/height or using an aspect-ratio helps the browser reserve space before images load, reducing CLS (layout shift) and improving perceived performance.

Why use precise autocomplete values instead of on/off?

Exact values like email or new-password improve form usability, accessibility, and security by guiding the browser’s autofill and providing correct keyboard behavior.

When should I add rel="noopener noreferrer" with target="_blank"?

Always when opening external links in a new tab to prevent the new page from accessing your window object and to avoid leaking referrer information.

HTML

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@ivangdavila

npx machina-cli add skill @ivangdavila/html --openclaw

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SKILL.md

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Layout Shift Prevention

width and height on <img> even with CSS sizing — browser reserves space before load
aspect-ratio in CSS as fallback — for responsive images without dimensions

Form Gotchas

autocomplete attribute is specific — autocomplete="email", autocomplete="new-password", not just on/off
<fieldset> + <legend> required for radio/checkbox groups — screen readers announce the group label
inputmode for virtual keyboard — inputmode="numeric" shows number pad without validation constraints
enterkeyhint changes mobile keyboard button — enterkeyhint="search", enterkeyhint="send"

Accessibility Gaps

Skip link must be first focusable — <a href="#main" class="skip">Skip to content</a> before nav
<th scope="col"> or scope="row" — without scope, screen readers can't associate headers
aria-hidden="true" hides from screen readers — use for decorative icons, not interactive elements
role="presentation" on layout tables — if you must use tables for layout (you shouldn't)

Link Security

target="_blank" needs rel="noopener noreferrer" — noopener prevents window.opener access, noreferrer hides referrer
User-generated links need rel="nofollow ugc" — ugc tells search engines it's user content

SEO Meta

<link rel="canonical"> prevents duplicate content — self-referencing canonical on every page
og:image needs absolute URL — relative paths fail on social platforms
twitter:card values: summary, summary_large_image, player — not arbitrary

Common Oversights

<button type="button"> for non-submit — default is type="submit", triggers form submission
<dialog> element for modals — built-in focus trap and escape handling
<details> + <summary> for accordions — no JS needed, accessible by default
Void elements don't need closing slash — <img> not <img /> in HTML5, though both work

Source

git clone https://clawhub.ai/ivangdavila/htmlView on GitHub

Overview

HTML helps you fix common mistakes that hurt accessibility, form usability, and search visibility. It shows practical patterns for preventing layout shifts, structuring forms, and securing meta and social tags. Implementing these practices improves user experience, assistive-tech compatibility, and search performance.

How This Skill Works

The skill translates guidelines into concrete markup patterns you can apply directly, such as sizing images with width/height or aspect-ratio fallbacks and using proper form semantics like autocomplete values and fieldset/legend groups. It also covers accessibility landmarks, skip links, and correct table header scopes, plus security and SEO patterns like rel attributes and canonical/meta tags. By following these patterns, you can reliably improve page stability, accessibility, and discoverability.

When to Use It

When optimizing image load performance to prevent layout shifts
When building accessible forms with precise autocomplete values and grouped controls
When structuring tables and navigation for screen readers with proper scopes and landmarks
When securing external links and handling user-generated URLs
When boosting SEO and social previews with canonical links and absolute social image URLs

Quick Start

Step 1: Audit your HTML for image sizing, form semantics, skip links, and SEO tags
Step 2: Apply concrete fixes: add width/height or aspect-ratio, set autocomplete values, group fields with fieldset/legend, and add appropriate rel canonical/og:image
Step 3: Validate with accessibility and SEO tools, test keyboard navigation, and verify social previews

Best Practices

Set width/height on images or use an aspect-ratio fallback to prevent CLS
Use precise autocomplete values (e.g., email, new-password) instead of generic on/off
Wrap radio/checkbox groups in fieldset with a legend for screen readers
Apply inputmode and enterkeyhint to tailor mobile keyboards
Place skip navigation first and ensure proper scope attributes for tables and headers

Example Use Cases

Product page uses explicit image width/height to eliminate layout shifts during load
Signup form uses autocomplete='email' and a dedicated new-password field for security
Modal dialog implemented with a native dialog element for built-in focus management
Details/summary used for accordion-style content to avoid extra JS while remaining accessible
External links include rel='noopener noreferrer' and pages implement canonical and absolute og:image URLs

Frequently Asked Questions

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