sass-site/source/documentation/at-rules/css.html.md.erb

---
title: CSS At-Rules
---

Sass supports all the at-rules that are part of CSS proper. To stay flexible and
forwards-compatible with future versions of CSS, Sass has general support that
covers almost all at-rules by default. A CSS at-rule is written
`@<name> <value>`, `@<name> { ... }`, or `@<name> <value> { ... }`. The value
(if one exists) can be pretty much anything, and can contain [interpolation][].

[interpolation]: ../interpolation

<% example do %>
@namespace svg url(http://www.w3.org/2000/svg);

@font-face {
  font-family: "Open Sans";
  src: url("/fonts/OpenSans-Regular-webfont.woff2") format("woff2");
}

@counter-style thumbs {
  system: cyclic;
  symbols: "\1F44D";
}
===
@namespace svg url(http://www.w3.org/2000/svg)

@font-face
  font-family: "Open Sans"
  src: url("/fonts/OpenSans-Regular-webfont.woff2") format("woff2")

@counter-style thumbs
  system: cyclic
  symbols: "\1F44D"
<% end %>

If a CSS at-rule is nested within a style rule, the two automatically swap
positions so that the at-rule is at the top level of the CSS output and the
style rule is within it. This makes it easy to add conditional styling without
having to rewrite the style rule's selector.

<% example do %>
.print-only {
  display: none;

  @media print { display: block; }
}
===
.print-only
  display: none

  @media print
    display: block
<% end %>

## `@media`

The [`@media` rule][] does all of the above and more. In addition to allowing
interpolation, it allows [SassScript expressions][] to be used directly in the
[feature queries][].

[`@media` rule]: https://developer.mozilla.org/en-US/docs/Web/CSS/Media_Queries/Using_media_queries
[SassScript expressions]: ../syntax/structure#expressions
[feature queries]: https://developer.mozilla.org/en-US/docs/Web/CSS/Media_Queries/Using_media_queries#Targeting_media_features

<% example do %>
$layout-breakpoint-small: 960px;

@media (min-width: $layout-breakpoint-small) {
  .hide-extra-small {
    display: none;
  }
}
===
$layout-breakpoint-small: 960px

@media (min-width: $layout-breakpoint-small)
  .hide-extra-small
    display: none
<% end %>

When possible, Sass will also merge media queries that are nested within one
another to make it easier to support browsers that don't yet natively support
nested `@media` rules.

<% example do %>
@media (hover: hover) {
  .button:hover {
    border: 2px solid black;

    @media (color) {
      border-color: #036;
    }
  }
}
===
@media (hover: hover)
  .button:hover
    border: 2px solid black

    @media (color)
      border-color: #036
<% end %>

## `@supports`

The [`@supports` rule][] also allows [SassScript expressions][] to be used in
the declaration queries.

[`@supports` rule]: https://developer.mozilla.org/en-US/docs/Web/CSS/@supports

<% example do %>
@mixin sticky-position {
  position: fixed;
  @supports (position: sticky) {
    position: sticky;
  }
}

.banner {
  @include sticky-position;
}
===
@mixin sticky-position
  position: fixed
  @supports (position: sticky)
    position: sticky



.banner
  @include sticky-position
<% end %>