How Do Nested @media Rules Work in CSS and What Browser Support Exists?

Nesting @media Rules in CSS

When working with CSS media queries, developers may encounter inconsistencies across browsers when attempting to nest @media rules within a conditional @import. This article will delve into the nuances of nesting @media rules, exploring browser support and the underlying reasons for varying behaviors.

Browser Support

Historically, support for nesting @media rules was limited due to the lack of such a feature in CSS2.1. However, the advent of CSS3's Conditional Rules module introduced the ability to nest @media rules, allowing for more granular control over styles based on media conditions.

Currently, all modern browsers, including Firefox, Safari, Chrome (and its derivatives), and Microsoft Edge, support nesting of @media rules as described in CSS Conditional 3. This means that the code in question with the nested @media at-rules should now work correctly everywhere, with the exception of Internet Explorer (which is no longer in development).

Terminology Clarification

It's important to note that the term "@media rules" refers to the entire block of code consisting of @media, the media query, and the rules nested within its curly braces. "@media query" specifically refers to the media condition portion of the rule.

Nesting vs. Conditional @import

Confusingly, media queries can also be used in @import rules, which raises questions about how they interact. The key distinction to keep in mind is that @import with a media query restricts the application of the imported stylesheet, while @media rules restrict the application of styles within a stylesheet.

In the example provided, the @media rule within the imported stylesheet works correctly in Firefox, despite the use of a media query in the @import statement. This is because these are two separate mechanisms for applying styles conditionally.

Enforcing Consistency

To ensure consistent behavior across browsers, developers can either use the conditional @import statement or remove the nesting of the @media rules. The latter option is recommended since both rules in the example use min-width media conditions.

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