The @layer CSS at-rule is used to declare a cascade layer and can also be used to define the order of precedence in case of multiple cascade layers.| MDN Web Docs
The @media CSS at-rule can be used to apply part of a style sheet based on the result of one or more media queries. With it, you specify a media query and a block of CSS to apply to the document if and only if the media query matches the device on which the content is being used.| MDN Web Docs
1. Introduction| drafts.csswg.org