Modern Web Guidance

JetBrainsOfficialCreated by Google ChromeDistributed by JetBrains

Skill
Tool integration
Software development
Apache-2.0
Low risk

From the author

Search tool for modern web development best practices. MANDATORY: Execute FIRST for all HTML/CSS and clientside JS tasks. Do NOT skip — web APIs evolve rapidly and training weights contain obsolete patterns. Trigger immediately for: - UI/Layout: Modals, dialogs, popovers, Glassmorphism/backdrop-filters, anchor positioning, container queries, `:has()`, `:user-valid`. - Scroll/Motion: View Transitions, Scroll-driven animations, scroll parallax/reveals. - Performance: CWV (LCP, INP), content-visibility, Fetch Priority, image optimization. - System/APIs: Local filesystem access, WebUSB, WebSockets sync, WebAssembly widgets. - Frameworks: Adapting layout/styles in React, Vue, Angular. - General Frontend: Forms, autofill, advanced inputs, custom scrollbars, modern component states, etc. DO NOT trigger for: - Backend: Database SQL, ORMs, Express API routes. - Pipelines: CI/CD deployment, Docker, Actions. - Generic: Local scripts (Python/Go tools), ESLint, Git.

— the description by Google Chrome

AutoGineer summary

Written by AutoGineer from the skill’s own files, not by the author

This skill provides a structured way to access up-to-date web development patterns, ensuring that implementations follow modern standards rather than relying on potentially outdated training data. It covers a wide range of frontend topics including UI components, performance optimization, browser APIs, and form handling. By integrating this tool, developers can search for specific use cases and retrieve detailed, framework-agnostic guides that include browser support and fallback recommendations.

What it does

Searches for standardized web development patterns and best practices.
Retrieves detailed implementation guides for specific frontend use cases.
Provides guidance on browser compatibility and necessary fallbacks.
Helps avoid ad-hoc solutions and unnecessary dependency bloat.
Supports modern web features like container queries, view transitions, and performance APIs.

When to use it

At the beginning of any frontend feature implementation.
Before creating new components to check for existing standardized patterns.
When evaluating the browser support requirements for modern web features.
When needing to implement performance optimizations like LCP or content-visibility.

Advantages

Ensures use of current, recommended web development practices.
Reduces technical debt by discouraging ad-hoc implementations.
Provides clear guidance on handling browser compatibility and fallbacks.
Promotes the use of native browser capabilities over heavy external dependencies.

Usage examples

“I need to implement a modal using modern web standards. What is the best approach?”: The agent searches for modal-related guides and retrieves the recommended implementation pattern, including any necessary browser fallbacks.
“How can I optimize the loading priority of my LCP images?”: The agent searches for image optimization guides and retrieves the specific instructions for using fetch priority to improve performance.

Install

Download the skill as a ZIP:
https://autogineer.com/agent-skills/jetbrains/modern-web-guidance/download

Unzip it into the cross-client skills folder of your project:

mkdir -p .agents/skills && unzip modern-web-guidance.zip -d .agents/skills

Documentation by Google Chrome

Modern Web Guidance

A skill to search for specific web development use cases and retrieve their corresponding best practice guides.

When to use

Must use this skill:

At the start of implementing any web feature.
Before creating a new component, to check if a standardized pattern already exists.
To avoid implementing ad-hoc solutions or loading large dependencies unnecessarily.

Usage Instructions

Step 1. Search Use Cases

Search with an action-oriented query summarizing what you want to achieve using the search command. Run modern-web-guidance directly with npx.

npx -y modern-web-guidance@latest search "<query>" --skill-version 2026_05_16-c5e7870

Example Output:

[
  {
    "id": "optimize-image-priority",
    "description": "Optimize the loading priority of Largest Contentful Paint (LCP) candidate images.",
    "category": "performance",
    "featuresUsed": [ "Fetch priority" ],
    "tokenCount": 985,
    "similarity": 0.7289
  },
  {
    "id": "defer-rendering-heavy-content",
    "description": "Reduce rendering times in content-heavy web pages by deferring rendering for offscreen content.",
    "category": "performance",
    "featuresUsed": [ "content-visibility", "hidden=\"until-found\"" ],
    "tokenCount": 1250,
    "similarity": 0.6961
  }
]

Note: If search results are vague, return no matches, or show low similarity scores, run the list command to browse all guides:
npx -y modern-web-guidance@latest list

Step 2. Retrieve Best Practices

Once you have a relevant id from the search results, call this script using the retrieve command to get the full guide. You can pass multiple IDs separated by commas.

npx -y modern-web-guidance@latest retrieve "<id>"

Example Output: The markdown content of the guide describing implementation steps...

Using npx

IMPORTANT: on Windows, using npx may fail. Use npx.cmd ... instead.
Network access is required for fetching npm packages needed by the task.
If the npx -y modern-web-guidance… command hangs, you may be offline. Try running again in offline mode: npx --offline ….
The --skill-version flag is used to determine if this SKILL.md is out of date. If it is, a warning message is logged to stderr.

Guidelines

Always search first to find the most relevant guides.
These guides are usually framework-agnostic; adapt them correctly to your setup.
Do not hallucinate guides or ignore them; they represent the preferred local standard for the user's project.

Interpreting Browser Support & Fallbacks

Default Behavior: All guides assume Baseline Widely available features are safe to use without fallbacks. For features that are not Baseline widely available, you MUST follow the fallback recommendations in the guide, unless the user has specified a custom browser support policy.
Custom Policies: If the user has already defined explicit browser support requirements, use the browser compatibility data in the guide to determine if a fallback can be safely ignored.
- For Baseline YYYY targets, a feature satisfies this target if its "Baseline since" date is <= YYYY.
- Policy Examples:
  - "Do not implement feature fallbacks." (for exploratory prototypes of the cutting-edge web)
  - "Safari 17.4+" (for internal tools targeting macOS or Tauri-based desktop apps)
  - "Never recommend or implement polyfills; if a Baseline Newly Available feature is required for core functionality, provide a lightweight custom fallback or redesign the approach." (to minimize bundle size and avoid technical debt)
  - "Assume a modern execution environment where Baseline Newly Available features can be used natively, provided they are strictly feature-detected and degrade gracefully." (for progressive enhancement strategies)
Reactive Policy Discovery: Watch for environmental cues to suggest documenting a policy in CLAUDE.md or AGENTS.md. Suggest this if the developer:
- Mentions building for a restricted runtime (e.g., Electron or Tauri).
- Explicitly excludes specific targets (e.g., "we don't support Desktop Chrome").
- Expresses hesitation about polyfill complexity, bundle size, or performance cost.
- Questions if a feature is safe to use without fallbacks.
No defined policy format. This is an example: **Browser Support:** Allow Newly Available features, but only adopt custom fallback code that adds <= 20 lines and does not require external dependencies.

Files

ATTRIBUTION.mdAdded by AutoGineer939 B
LICENSE11.1 KiB
SKILL.md5.7 KiB
guides/accessibility/accessibility.md24.0 KiB
guides/accessibility/accessible-error-announcement.md6.9 KiB
guides/built-in-ai/language-detection.md3.5 KiB
guides/built-in-ai/language-model.md7.1 KiB
guides/built-in-ai/summarizer.md5.9 KiB
guides/built-in-ai/translator.md5.3 KiB
guides/css-layout/css-layout.md19.5 KiB
guides/css/css.md27.0 KiB
guides/css/highlight-text-ranges.md5.4 KiB
guides/forms/animated-select-picker.md7.8 KiB
guides/forms/autofill-address-form.md4.1 KiB
guides/forms/autofill-highlight-inputs.md2.3 KiB
guides/forms/autofill-payment-form.md8.5 KiB
guides/forms/autofill-sign-in-form.md9.9 KiB
guides/forms/autofill-sign-up-form.md11.0 KiB
guides/forms/brand-consistent-forms.md8.3 KiB
guides/forms/branded-select-styling.md5.5 KiB
guides/forms/custom-select-picker-layouts.md5.0 KiB
guides/forms/form-fields-automatically-fit-contents.md5.8 KiB
guides/forms/forms.md13.8 KiB
guides/forms/required-field-feedback.md6.8 KiB
guides/forms/rich-media-picker.md6.6 KiB
guides/forms/select-menu-interaction.md5.6 KiB
guides/forms/validate-input-after-interaction.md8.6 KiB
guides/html/html.md17.5 KiB
guides/passkeys/passkey-authentication.md9.7 KiB
guides/passkeys/passkey-conditional-create.md6.5 KiB
guides/passkeys/passkey-management.md9.3 KiB
guides/passkeys/passkey-reauthentication.md4.9 KiB
guides/passkeys/passkey-registration.md9.3 KiB
guides/passkeys/passkeys.md4.2 KiB
guides/performance/batch-analytics-events.md6.4 KiB
guides/performance/break-up-long-tasks.md2.1 KiB
guides/performance/calculate-total-foreground-time.md2.9 KiB
guides/performance/conditional-async-dependencies.md3.6 KiB
guides/performance/defer-rendering-heavy-content.md6.3 KiB
guides/performance/defer-work-until-scroll-ends.md3.3 KiB
guides/performance/deprioritize-background-fetches.md1.8 KiB
guides/performance/detect-initial-visibility-state.md4.5 KiB
guides/performance/efficient-background-processing.md5.0 KiB
guides/performance/faster-spa-view-transitions.md3.4 KiB
guides/performance/full-session-analytics.md5.7 KiB
guides/performance/identify-heavy-scripts.md4.2 KiB
guides/performance/identify-inp-causes.md5.4 KiB
guides/performance/improve-next-page-load-performance.md7.1 KiB
guides/performance/interactions-in-complex-layouts.md3.4 KiB
guides/performance/optimize-image-priority.md4.0 KiB
guides/performance/optimize-preload-priority.md3.3 KiB
guides/performance/optimize-script-priority.md2.6 KiB
guides/performance/performance.md17.9 KiB
guides/performance/resolution-optimized-pseudo-elements.md2.3 KiB
guides/performance/schedule-tasks-by-priority.md2.2 KiB
guides/performance/sequence-distributed-events.md3.5 KiB
guides/privacy/privacy.md11.0 KiB
guides/security/security.md25.2 KiB
guides/user-experience/adapt-scrollbar-to-contrast-preferences.md3.5 KiB
guides/user-experience/anchor-positioning-tab-underline.md2.9 KiB
guides/user-experience/animate-element-entry-exit.md5.0 KiB
guides/user-experience/animate-to-from-top-layer.md5.5 KiB
guides/user-experience/animate-to-intrinsic-sizes.md5.3 KiB
guides/user-experience/apply-webgl-shaders.md9.9 KiB
guides/user-experience/calculate-event-differentials.md4.4 KiB
guides/user-experience/calculate-with-intrinsic-sizes.md9.6 KiB
guides/user-experience/capture-location-agnostic-data.md3.6 KiB
guides/user-experience/carousel-slide-effects.md8.1 KiB
guides/user-experience/carousel-snap-highlights.md5.7 KiB
guides/user-experience/child-state-based-styling.md4.8 KiB
guides/user-experience/complex-shapes.md3.5 KiB
guides/user-experience/component-specific-light-dark-theme.md9.3 KiB
guides/user-experience/consistent-cross-document-transitions.md11.8 KiB
guides/user-experience/content-based-styling.md5.2 KiB
guides/user-experience/coordinate-global-events.md3.5 KiB
guides/user-experience/cross-document-transitions.md4.4 KiB
guides/user-experience/customize-scrollbar-color-and-thickness.md2.4 KiB
guides/user-experience/dark-mode.md15.2 KiB
guides/user-experience/declarative-button-actions.md5.4 KiB
guides/user-experience/declarative-dialog-popover-control.md9.2 KiB
guides/user-experience/deliver-optimized-decorative-images.md2.8 KiB
guides/user-experience/design-token-reactivity.md5.7 KiB
guides/user-experience/directional-navigation-transitions.md4.9 KiB
guides/user-experience/dynamic-sibling-animations.md2.6 KiB
guides/user-experience/dynamic-sibling-styling.md3.6 KiB
guides/user-experience/export-html-media-from-canvas.md11.2 KiB
guides/user-experience/expose-canvas-content-to-browser-features.md14.1 KiB
guides/user-experience/flicker-free-client-side-ab-testing.md8.5 KiB
guides/user-experience/fluid-scaling.md3.0 KiB
guides/user-experience/format-human-readable-durations.md4.2 KiB
guides/user-experience/group-element-transitions.md5.0 KiB
guides/user-experience/improve-text-layout-and-legibility.md5.1 KiB
guides/user-experience/individual-transform-properties.md3.6 KiB
guides/user-experience/interactive-content-in-3d-scenes.md13.3 KiB
guides/user-experience/interactive-content-reveal.md5.1 KiB
guides/user-experience/interest-triggered-action-previews.md4.1 KiB
guides/user-experience/interest-triggered-tooltips.md6.8 KiB
guides/user-experience/light-dismiss-a-dialog.md3.6 KiB
guides/user-experience/manage-recurring-intervals.md3.3 KiB
guides/user-experience/model-partial-time-concepts.md4.2 KiB
guides/user-experience/move-dom-element-without-losing-state.md2.5 KiB
guides/user-experience/navigation-drawer.md15.7 KiB
guides/user-experience/overflow-clipping-control.md8.0 KiB
guides/user-experience/parallax-scroll-effects.md8.8 KiB
guides/user-experience/persistent-app-tours.md3.9 KiB
guides/user-experience/persistent-toast-notifications.md1.8 KiB
guides/user-experience/persistent-top-layer-ui.md2.2 KiB
guides/user-experience/physics-based-easing.md5.8 KiB
guides/user-experience/platform-controls-dismiss-dialog.md2.6 KiB
guides/user-experience/position-aware-tooltips.md5.9 KiB
guides/user-experience/precise-text-alignment.md4.7 KiB
guides/user-experience/prevent-text-wrapping.md2.4 KiB
guides/user-experience/pull-to-reveal.md4.7 KiB
guides/user-experience/reduce-style-repetition.md3.9 KiB
guides/user-experience/resilient-context-menus-and-nested-dropdowns.md4.9 KiB
guides/user-experience/same-document-transitions.md8.3 KiB
guides/user-experience/scroll-entry-exit-effects.md7.8 KiB
guides/user-experience/scroll-position-aware-elements.md3.6 KiB
guides/user-experience/scroll-progress-indicator.md6.7 KiB
guides/user-experience/scroll-snap-realtime-feedback.md6.7 KiB
guides/user-experience/scroll-snap-state-sync.md3.9 KiB
guides/user-experience/scroll-target-on-load.md3.3 KiB
guides/user-experience/scrollability-affordance-hints.md3.6 KiB
guides/user-experience/scrollytelling.md8.3 KiB
guides/user-experience/search-hidden-content.md6.7 KiB
guides/user-experience/shaped-cutouts.md7.0 KiB
guides/user-experience/shrinking-header-on-scroll.md6.3 KiB
guides/user-experience/size-aware-styling.md2.9 KiB
guides/user-experience/soft-edge-content-fade.md2.6 KiB
guides/user-experience/stabilize-reactive-state.md3.5 KiB
guides/user-experience/stack-drill-down.md32.9 KiB
guides/user-experience/style-parent-with-has.md6.0 KiB
guides/user-experience/support-global-calendar-systems.md5.7 KiB
guides/user-experience/swipe-to-remove.md26.2 KiB
guides/user-experience/visually-stable-font-fallbacks.md2.9 KiB
guides/user-experience/visually-stable-mixed-fonts.md2.8 KiB
guides/user-experience/visually-texture-content.md3.7 KiB
guides/webmcp/agentic-forms.md5.0 KiB
guides/webmcp/agentic-javascript-tools.md4.1 KiB
guides/webmcp/webmcp.md3.7 KiB

guides/user-experience/adapt-scrollbar-to-contrast-preferences.md

Adapt scrollbar to high-contrast preferences

Users who enable high-contrast modes in their operating system or browser expect UI elements (like scrollbars) to be extremely legible, often relying on stark foreground-background separation rather than subtle grays or theme colors.

This guide provides optional instructions on how to use the @media (prefers-contrast: more) CSS media feature to enforce high-contrast scrollbar styling.

Enhance Legibility

When customizing scrollbars with scrollbar-color or custom variables, you can provide an explicit override for high-contrast modes. This is especially helpful if your primary application theme uses low-contrast scrollbars for aesthetic reasons.

OPTIONAL: Use a @media (prefers-contrast: more) block to define dark, distinct colors for the thumb and track.

/* Define default standard colors as variables */
.scroller {
  --scrollbar-thumb: #bbb;
  --scrollbar-track: #f1f1f1;

  scrollbar-color: var(--scrollbar-thumb) var(--scrollbar-track);
  scrollbar-width: thin;
  scrollbar-gutter: stable;
}

/* OPTIONAL: Provide clear, high-contrast overrides */
@media (prefers-contrast: more) {
  .scroller {
    /* Use extremely distinct colors like solid black against white */
    --scrollbar-thumb: #000000;
    --scrollbar-track: #ffffff;
  }
}

Issues to be aware of when using scrollbar-color

Do NOT animate or transition scrollbar-color. A WebKit bug causes the scrollbar to flicker every time scrollbar-color changes.
On macOS, scrollbar-color (standard) and ::-webkit-scrollbar (legacy) properties are ignored by default because macOS uses native "overlay" scrollbars. You MUST pair custom colors with scrollbar-width (e.g., thin or auto) to force macOS to render them.
Even with scrollbar-width applied, macOS overlay scrollbars render the track (gutter) as transparent by default. If the design requires a visible track background color on MacOS, you MUST apply scrollbar-gutter: stable; to the scrollable container, but note that it only appears after the user hovers over the scrollbar.
Even with scrollbar-gutter: stable the track may be transparent on MacOS. The thumb should not depend on the track color to be visible.

Fallbacks & Browser Support

Fallbacks & browser support for scrollbar-color

Baseline status for scrollbar-color: Newly available. It's been Baseline since 2025-12-12. Supported by: Chrome 121 (Jan 2024), Edge 121 (Jan 2024), Firefox 64 (Dec 2018), and Safari 26.2 (Dec 2025).

This feature is progressive enhancement and does not always require fallbacks.

If the styling is important and the user's Baseline target is "Baseline Widely Available" or earlier, you SHOULD include the non-standard ::-webkit-scrollbar pseudo-elements as fallbacks.

Wrap legacy fallbacks in an @supports not (scrollbar-color: auto) block to prevent conflicts between standard properties and legacy WebKit selectors in browsers that support both natively.

If you are using custom properties to define colors, these will cascade to the legacy WebKit selectors automatically. You do NOT need to duplicate them.

/* Legacy fallback for WebKit/Blink browsers */
@supports not (scrollbar-color: auto) {
  .scroller::-webkit-scrollbar {
    /* Must define base size in WebKit for custom colors to be visual */
    width: 12px;
    height: 12px;
  }

  .scroller::-webkit-scrollbar-thumb {
    background: var(--scrollbar-thumb);
  }

  .scroller::-webkit-scrollbar-track {
    background: var(--scrollbar-track);
  }
}

Requirements and compatibility

Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta

“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.

Needs: Needs Node.js

Security

What our scanner noticed· Low risk

Instructions that use the network

A static scan is not a guarantee. Skills are third-party content: review a skill before you let an agent use it.

Attribution and licence

Created by

Google Chrome

Publisher

JetBrains (Official)

Distributed by

JetBrains

Source

JetBrains/skills · modern-web-guidance · commit 3f53782

Licence

Apache License 2.0 (redistribution allowed)

ATTRIBUTION.md (written by AutoGineer)

Synced

2026-11-09

AutoGineer is not affiliated with or endorsed by Google Chrome or JetBrains.

Download ZIP

The ZIP holds the skill’s files, its licence files and an ATTRIBUTION.md. Download modern-web-guidance.zip

From the author

AutoGineer summary

What it does

When to use it

Advantages

Usage examples

Install

Documentation by Google Chrome

Modern Web Guidance

When to use

Usage Instructions

Step 1. Search Use Cases

Step 2. Retrieve Best Practices

Using npx

Guidelines

Interpreting Browser Support & Fallbacks

Files

guides/user-experience/adapt-scrollbar-to-contrast-preferences.md

Adapt scrollbar to high-contrast preferences

Enhance Legibility

Issues to be aware of when using scrollbar-color

Fallbacks & Browser Support

Fallbacks & browser support for scrollbar-color

Requirements and compatibility

Security

Attribution and licence

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Pick UI Library

Animate Expo

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