Breaking Change: Media Queries Level 4

Sass is adding support for the CSS Media Queries Level 4 specification, but this conflicts with some Sass-specific syntax. That syntax is deprecated to ensure that Sass remains fully CSS-compatible.

Because Sass supports almost any Sass expression in parenthesized media conditions, there are a few constructs that could be broken by adding full support for Media Queries Level 4. Specifically:

  • @media (not (foo)) was historically interpreted by Sass as meaning @media (#{not (foo)}), and so compiled to @media (false).

  • @media ((foo) and (bar)) and @media ((foo) or (bar)) were similarly interpreted as SassScript’s logical operators, compiling to @media (bar) and @media (foo) respectively.

Fortunately, these are unlikely to come up in practice.

Transition Period permalinkTransition Period

Compatibility:
Dart Sass
since 1.54.0
LibSass
Ruby Sass

First, we’ll emit deprecation warnings for the previous ambiguous cases. These will have suggestions for how to preserve the existing behavior or how to use the new CSS syntax.

Once the deprecation warnings have been out for at least three months, we’ll release a version that exclusively interprets these ambiguous cases according to the CSS spec.