2.1.29 [CSS-Level2-2009] Section 7.2.1, The @media rule

V0029:

The specification states:

 Style rules outside of @media rules apply to all media types that the style sheet 
 applies to. At-rules inside @media are invalid in CSS2.1.

 Quirks Mode and IE7 Mode (All Versions)

At-rules inside the @media rule are not ignored. For example, if an @media appears inside an @media rule, the declarations within are applied to the document.