The @supports rule in CSS allows you to apply styles conditionally based on whether a browser supports a specific CSS feature. 1. It works by checking if a browser recognizes a given property-value pair, such as @supports (display: grid). 2. You can use logical operators like and, or, and not to create more complex conditions. 3. Feature queries enable progressive enhancement by letting you safely use modern CSS features while providing fallbacks for older browsers. 4. They are useful for testing layout techniques like CSS Grid, subgrid, or container queries, and for combining feature checks with media queries. 5. Best practices include using @supports selectively, testing layouts manually, and writing base styles first before enhancing them within a @supports block.
CSS feature queries, using the @supports rule, let you apply styles only if a browser supports a specific CSS feature. It’s like asking the browser, “Hey, can you do this?” and then giving it instructions based on the answer.
This is super useful when working with newer CSS features that might not be available in all browsers yet.
How to Use @supports
The basic syntax looks like this:
@supports (property: value) {
/* Styles go here */
}You just write a condition inside the parentheses — usually a CSS property and value pair. If the browser recognizes that combination, it will apply the styles inside the block.
For example:
@supports (display: grid) {
.container {
display: grid;
grid-template-columns: repeat(3, 1fr);
}
}In this case, only browsers that support CSS Grid will use those styles.
Here are a few more examples of valid conditions:
@supports (transform: rotate(30deg))@supports not (text-stroke: 2px red)@supports (filter: blur(2px)) or (-webkit-filter: blur(2px))
You can also combine conditions using and, or, and not.
Why Feature Queries Are Useful
Feature queries help you write progressive enhancement-friendly code. You don’t have to guess what browser someone is using — you just check whether the browser can handle a particular style.
Here are a few real-world uses:
- Use modern layout techniques safely: Try out things like
aspect-ratio,subgrid, orcontainer querieswithout breaking older browsers. - Provide fallbacks: If a feature isn't supported, you can fall back to an older layout method like Flexbox or floats.
- Test combinations: You can check for multiple features at once. For example, only apply a style if both
backdrop-filterand@media (prefers-reduced-transparency)are supported.
Without feature queries, you might end up relying on browser detection, which is less reliable and harder to maintain.
A Few Gotchas and Tips
- Don’t test for everything: Only use
@supportswhen necessary. Most CSS already fails gracefully when a browser doesn’t understand something. - Not all features can be tested perfectly: Some properties may technically exist but behave differently across browsers. So always test your layouts manually too.
- Nesting works: You can nest
@supportsinside media queries (or vice versa), allowing for very targeted styling.
A good pattern is to write base styles first, then enhance them inside a @supports block.
Like this:
.my-box {
width: 100%;
}
@supports (width: stretch) {
.my-box {
width: stretch;
}
}That way, everyone gets something usable, and modern browsers get the better version.
So basically, @supports gives you a clean, native way to write conditional CSS — no JavaScript or external tools needed. It's not something you'll use every day, but it's a solid tool to have when you're pushing the edge of modern CSS.
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