Container Query Conundrum: Why It Doesn’t Work in Inline or External CSS Files in Astro
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Container Query Conundrum: Why It Doesn’t Work in Inline or External CSS Files in Astro

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Are you excited to dive into the world of container queries in Astro? Well, hold your horses, friend! You might have noticed that your container queries aren’t working as expected when defined in inline styles or external CSS files. Don’t worry, you’re not alone. In this article, we’ll explore the reasons behind this phenomenon and provide you with actionable solutions to get your container queries up and running.

Table of Contents
  1. What are Container Queries?
  2. The Problem: Container Queries Don’t Work in Inline or External CSS Files
    1. Solution 1: Use aastro Styles
    2. Solution 2: Use a Preprocessor like Sass or Less
    3. Solution 3: Use a CSS-in-JS Solution like Astro’s Built-in CSS
  3. Conclusion
  4. Frequently Asked Questions
    1. Why don’t container queries work in inline styles?
    2. Can I use container queries in external CSS files?
    3. What’s the best way to define container queries in Astro?

What are Container Queries?

Container queries are a game-changer in the world of CSS. They allow you to write styles that respond to the size of a container, rather than the viewport. This means you can create layouts that adapt to their surroundings, making your design more flexible and responsive. In Astro, container queries are defined using the `@container` at-rule.


.container {
  container-type: inline-size;
  inline-size: 300px;
}

@container (min-inline-size: 300px) {
  .container {
    background-color: red;
  }
}

The Problem: Container Queries Don’t Work in Inline or External CSS Files

So, you’ve defined your container query, but it’s not working as expected. You’ve tried adding it to your inline styles, external CSS files, or even a CSS framework like Tailwind CSS, but to no avail. What’s going on?

The reason behind this issue lies in how Astro processes CSS. When Astro encounters a container query, it needs to be able to access the HTML element that the query is associated with. This is because container queries rely on the element’s size and context to determine when to apply the styles.

In the case of inline styles or external CSS files, Astro doesn’t have direct access to the HTML element. This means that the container query can’t function correctly, leading to unexpected results or no results at all.

Solution 1: Use aastro Styles

The simplest solution is to define your container queries using Astro’s built-in `aastro` styles. This approach allows Astro to process your CSS in a way that enables container queries to work as expected.


<style lang="aastro">
.container {
  container-type: inline-size;
  inline-size: 300px;
}

@container (min-inline-size: 300px) {
  .container {
    background-color: red;
  }
}
</style>

Note the use of the `lang=”aastro”` attribute in the `