CSS Container Queries: Responsive Design That Actually Makes Sense

For years, responsive design has depended almost entirely on media queries. We ask questions like:

“If the screen is 768px wide, do this.”
“If the screen is 1024px wide, change that.”

But modern web layouts are no longer just about the viewport. We build components that live inside cards, sidebars, modals, grids, and dashboards. A component might be wide in one place and narrow in another—even on the same screen.

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This is the problem CSS Container Queries solve.

Instead of responding to the screen size, elements can now respond to the size of their parent container.

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Why Media Queries Are No Longer Enough

Imagine a reusable card component:

• On desktop: it sits in a 3-column grid.
• On mobile: it becomes full-width.
• In a sidebar: it is very narrow.

With media queries, you only know the viewport width, not the card’s actual width. So the card’s layout might break when reused in different contexts.

Container queries flip the logic:

“Style this component based on how much space it actually has.”

What Are Container Queries?

Container queries allow an element to apply styles depending on the size of its container, not the viewport.

You define a container:

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

Then you query it:

@container (min-width: 400px) {
  .card {
    display: grid;
    grid-template-columns: 1fr 1fr;
  }
}

Meaning:

If the container is at least 400px wide, change the layout of .card.

Step 1: Defining a Container

To use container queries, you must mark an element as a container.

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

Common values:

• inline-size → responds to width (most common)
• size → responds to both width and height

You can also name containers:

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

Then target it like this:

@container layout (min-width: 600px) {
  .item {
    font-size: 1.2rem;
  }
}

Step 2: Writing a Container Query

Basic syntax:

@container (min-width: 500px) {
  /* styles */}

With class targeting:

@container (max-width: 300px) {
  .profile-card {
    flex-direction: column;
  }
}

This means:

When the parent container becomes narrow, stack the content vertically.

Real-World Example: A Responsive Card

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

.card {
  display: flex;
  gap: 1rem;
}

@container (max-width: 350px) {
  .card {
    flex-direction: column;
  }
}

Now the card automatically adapts when placed in:

• A wide main section → horizontal layout
• A narrow sidebar → vertical layout

No viewport logic. No hacks.

Container Queries vs Media Queries

Media Queries	Container Queries
Based on screen size	Based on parent size
Page-level logic	Component-level logic
Hard to reuse components	Perfect for reusable components
Layout-driven	Context-driven

They work best together, not as replacements.

Container Query Units

New units based on container size:

• cqw – 1% of container width
• cqh – 1% of container height
• cqi – inline size
• cqb – block size
• cqmin, cqmax

Example:

.title {
  font-size: 5cqw;
}

Font size now scales with the container, not the viewport.

Practical Use Cases

1. Dashboard widgets
   Each widget adapts to the column it’s placed in.
2. Card components
   Same card works in grids, modals, sidebars.
3. Design systems
   Truly responsive components, not page-specific ones.
4. Embeddable components
   Your UI adapts even when embedded in unknown layouts.

Browser Support

Container Queries are supported in all modern browsers:

• Chrome
• Edge
• Firefox
• Safari

They are now safe for production.

Mental Shift for Developers

Old thinking:

“How big is the screen?”

New thinking:

“How much space does this component have?”

This is a major shift toward true component-driven design, which aligns perfectly with modern frameworks like React, Vue, and Angular.

Final Thought

Media queries made websites responsive.
Container queries make components intelligent.

They are one of the biggest CSS breakthroughs in the last decade because they finally allow:

Layout logic to live where it belongs — inside the component itself.