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@be57c0b
by Seth Hobsonwshobson/agents40k stars
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Implement modern responsive layouts using container queries, fluid typography, CSS Grid, and mobile-first breakpoint strategies. Use when building adaptive interfaces, implementing fluid layouts, or creating component-level responsive behavior.

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referencescontainer-queries.md

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Container Queries Deep Dive

Overview

Container queries enable component-based responsive design by allowing elements to respond to their container's size rather than the viewport. This paradigm shift makes truly reusable components possible.

Browser Support

Container queries have excellent modern browser support (Chrome 105+, Firefox 110+, Safari 16+). For older browsers, provide graceful fallbacks.

Containment Basics

Container Types

/* Size containment - queries based on inline and block size */
.container {
  container-type: size;
}

/* Inline-size containment - queries based on inline (width) size only */
/* Most common and recommended */
.container {
  container-type: inline-size;
}

/* Normal - style queries only, no size queries */
.container {
  container-type: normal;
}

Named Containers

/* Named container for targeted queries */
.card-wrapper {
  container-type: inline-size;
  container-name: card;
}

/* Shorthand */
.card-wrapper {
  container: card / inline-size;
}

/* Query specific container */
@container card (min-width: 400px) {
  .card-content {
    display: flex;
  }
}

Container Query Syntax

Width-Based Queries

.container {
  container-type: inline-size;
}

/* Minimum width */
@container (min-width: 300px) {
  .element {
    /* styles */
  }
}

/* Maximum width */
@container (max-width: 500px) {
  .element {
    /* styles */
  }
}

/* Range syntax */
@container (300px <= width <= 600px) {
  .element {
    /* styles */
  }
}

/* Exact width */
@container (width: 400px) {
  .element {
    /* styles */
  }
}

Combining Conditions

/* AND condition */
@container (min-width: 400px) and (max-width: 800px) {
  .element {
    /* styles */
  }
}

/* OR condition */
@container (max-width: 300px) or (min-width: 800px) {
  .element {
    /* styles */
  }
}

/* NOT condition */
@container not (min-width: 400px) {
  .element {
    /* styles */
  }
}

Named Container Queries

/* Multiple named containers */
.page-wrapper {
  container: page / inline-size;
}

.sidebar-wrapper {
  container: sidebar / inline-size;
}

/* Target specific containers */
@container page (min-width: 1024px) {
  .main-content {
    max-width: 800px;
  }
}

@container sidebar (min-width: 300px) {
  .sidebar-widget {
    display: grid;
    grid-template-columns: 1fr 1fr;
  }
}

Container Query Units

/* Container query length units */
.element {
  /* Container query width - 1cqw = 1% of container width */
  width: 50cqw;

  /* Container query height - 1cqh = 1% of container height */
  height: 50cqh;

  /* Container query inline - 1cqi = 1% of container inline size */
  padding-inline: 5cqi;

  /* Container query block - 1cqb = 1% of container block size */
  padding-block: 3cqb;

  /* Container query min - smaller of cqi and cqb */
  font-size: 5cqmin;

  /* Container query max - larger of cqi and cqb */
  margin: 2cqmax;
}

/* Practical example: fluid typography based on container */
.card-title {
  font-size: clamp(1rem, 4cqi, 2rem);
}

.card-body {
  padding: clamp(0.75rem, 4cqi, 1.5rem);
}

Style Queries

Style queries allow querying CSS custom property values. Currently limited support.

/* Define a custom property */
.card {
  --layout: stack;
}

/* Query the property value */
@container style(--layout: stack) {
  .card-content {
    display: flex;
    flex-direction: column;
  }
}

@container style(--layout: inline) {
  .card-content {
    display: flex;
    flex-direction: row;
  }
}

/* Toggle layout via custom property */
.card.horizontal {
  --layout: inline;
}

Practical Patterns

Responsive Card Component

.card-container {
  container: card / inline-size;
}

.card {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  padding: clamp(1rem, 4cqi, 2rem);
}

.card-image {
  aspect-ratio: 16/9;
  width: 100%;
  object-fit: cover;
  border-radius: 0.5rem;
}

.card-title {
  font-size: clamp(1rem, 4cqi, 1.5rem);
  font-weight: 600;
}

/* Medium container: side-by-side layout */
@container card (min-width: 400px) {
  .card {
    flex-direction: row;
    align-items: flex-start;
  }

  .card-image {
    width: 40%;
    aspect-ratio: 1;
  }

  .card-content {
    flex: 1;
  }
}

/* Large container: enhanced layout */
@container card (min-width: 600px) {
  .card-image {
    width: 250px;
  }

  .card-title {
    font-size: 1.5rem;
  }

  .card-actions {
    display: flex;
    gap: 0.5rem;
  }
}

Responsive Grid Items

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1.5rem;
}

.grid-item {
  container-type: inline-size;
}

.item-content {
  padding: 1rem;
}

/* Item adapts to its own size, not the viewport */
@container (min-width: 350px) {
  .item-content {
    padding: 1.5rem;
  }

  .item-title {
    font-size: 1.25rem;
  }
}

@container (min-width: 500px) {
  .item-content {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 1rem;
  }
}

Dashboard Widget

.widget-container {
  container: widget / inline-size;
}

.widget {
  --chart-height: 150px;
  padding: 1rem;
}

.widget-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1rem;
}

.widget-chart {
  height: var(--chart-height);
}

.widget-stats {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.5rem;
}

@container widget (min-width: 300px) {
  .widget {
    --chart-height: 200px;
  }

  .widget-stats {
    grid-template-columns: repeat(2, 1fr);
  }
}

@container widget (min-width: 500px) {
  .widget {
    --chart-height: 250px;
    padding: 1.5rem;
  }

  .widget-stats {
    grid-template-columns: repeat(4, 1fr);
  }

  .widget-actions {
    display: flex;
    gap: 0.5rem;
  }
}

Navigation Component

.nav-container {
  container: nav / inline-size;
}

.nav {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.nav-link {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem 1rem;
  border-radius: 0.5rem;
}

.nav-link-text {
  display: none;
}

.nav-link-icon {
  width: 1.5rem;
  height: 1.5rem;
}

/* Show text when container is wide enough */
@container nav (min-width: 200px) {
  .nav-link-text {
    display: block;
  }
}

/* Horizontal layout for wider containers */
@container nav (min-width: 600px) {
  .nav {
    flex-direction: row;
  }

  .nav-link {
    padding: 0.5rem 1rem;
  }
}

Tailwind CSS Integration

// Tailwind v3.2+ supports container queries
// tailwind.config.js
module.exports = {
  plugins: [require("@tailwindcss/container-queries")],
};

// Component usage
function Card({ title, image, description }) {
  return (
    // @container creates containment context
    <div className="@container">
      <article className="flex flex-col @md:flex-row @md:gap-4">
        <img
          src={image}
          alt=""
          className="w-full @md:w-48 @lg:w-64 aspect-video @md:aspect-square object-cover rounded-lg"
        />
        <div className="p-4 @md:p-0">
          <h2 className="text-lg @md:text-xl @lg:text-2xl font-semibold">
            {title}
          </h2>
          <p className="mt-2 text-muted-foreground @lg:text-lg">
            {description}
          </p>
        </div>
      </article>
    </div>
  );
}

// Named containers
function Dashboard() {
  return (
    <div className="@container/main">
      <aside className="@container/sidebar">
        <nav className="flex flex-col @lg/sidebar:flex-row">{/* ... */}</nav>
      </aside>
      <main className="@lg/main:grid @lg/main:grid-cols-2">{/* ... */}</main>
    </div>
  );
}

Fallback Strategies

/* Provide fallbacks for browsers without support */
.card {
  /* Default (fallback) styles */
  display: flex;
  flex-direction: column;
}

/* Feature query for container support */
@supports (container-type: inline-size) {
  .card-container {
    container-type: inline-size;
  }

  @container (min-width: 400px) {
    .card {
      flex-direction: row;
    }
  }
}

/* Alternative: media query fallback */
.card {
  display: flex;
  flex-direction: column;
}

/* Viewport-based fallback */
@media (min-width: 768px) {
  .card {
    flex-direction: row;
  }
}

/* Enhanced with container queries when supported */
@supports (container-type: inline-size) {
  @media (min-width: 768px) {
    .card {
      flex-direction: column; /* Reset */
    }
  }

  @container (min-width: 400px) {
    .card {
      flex-direction: row;
    }
  }
}

Performance Considerations

/* Avoid over-nesting containers */
/* Bad: Too many nested containers */
.level-1 {
  container-type: inline-size;
}
.level-2 {
  container-type: inline-size;
}
.level-3 {
  container-type: inline-size;
}
.level-4 {
  container-type: inline-size;
}

/* Good: Strategic container placement */
.component-wrapper {
  container-type: inline-size;
}

/* Use inline-size instead of size when possible */
/* size containment is more expensive */
.container {
  container-type: inline-size; /* Preferred */
  /* container-type: size; */ /* Only when needed */
}

Testing Container Queries

// Test container query support
const supportsContainerQueries = CSS.supports("container-type", "inline-size");

// Resize observer for testing
const observer = new ResizeObserver((entries) => {
  for (const entry of entries) {
    console.log("Container width:", entry.contentRect.width);
  }
});

observer.observe(document.querySelector(".container"));

Resources

Source: SKILL.md on GitHub

Third-party checks

No alerts16d5 checks · Risk SAFE
  • Gen Agent Trust Hub16d

    The skill provides comprehensive documentation and code examples for implementing modern responsive design using CSS and JavaScript. No security vulnerabilities, malicious code, or suspicious patterns were detected.

  • Socket16d

    No alerts

  • Snyk16d

    Risk: LOW · No issues

  • Runlayer6mo

    4 files scanned · No issues

  • ZeroLeaks5mo

    Score: 93/100 · 2 sections analyzed

Provenance

Signed by skilld at be57c0b. This ties the file your Agent reads to that commit on GitHub. It does not review the instructions.

Last checked against GitHub 3 days ago.

Activeupdated 4 months ago

Topics

  • responsive-design
  • css-grid
  • flexbox
  • container-queries
  • mobile-first
  • breakpoints
  • fluid-typography
  • css
  • web-design
  • accessibility

README badge

README badge for wshobson/agents/responsive-design

What it does

Implements modern responsive layouts using container queries, fluid typography, CSS Grid, and mobile-first breakpoint strategies. Covers component-level responsiveness, fluid spacing scales, and adaptive patterns for navigation, tables, and images across all screen sizes.

Generated from the current SKILL.md.

Frequently asked

Does this skill cover container queries?
Yes. Container queries are listed as a core technique for implementing component-level responsive behavior without relying on viewport-based breakpoints.
What CSS layout methods does this skill teach?
The skill covers CSS Grid, Flexbox, and fluid typography/spacing scales, with emphasis on mobile-first breakpoint strategies.
Does this include guidance on responsive images?
Yes. Implementing responsive images and media is listed as a core use case, along with performance optimization like lazy loading.
Are there worked examples in the skill?
Pattern documentation and worked examples are provided in a `references/details.md` file bundled with the skill.

Generated from the current SKILL.md. These answers refresh after source changes.