Name Description Size Cascading at-rule types and traits 2190 A [`@container`][container] rule. [container]: 21016 304 [@document rules]( initially in CSS Conditional Rules Module Level 3, @document has been postponed to the level 4. We implement the prefixed `@-moz-document`. 11473 292 The [`@font-feature-values`][font-feature-values] at-rule. [font-feature-values]: 17501 The [`@font-palette-values`][font-palette-values] at-rule. [font-palette-values]: 9161 The [`@import`][import] at-rule. [import]: 6560 Keyframes: 23143 A [`@layer`][layer] rule. [layer]: 7324 The stylesheet loader is the abstraction used to trigger network requests for `@import` rules. 1093 An [`@media`][media] rule. [media]: 2631 Style sheets and their CSS rules. 20839 The `@namespace` at-rule. 1433 [CSS cascade origins]( 6943 A [`@page`][page] rule. [page]: 4812 A list of CSS rules. 5738 Parsing of the stylesheet contents. 31230 An iterator over a list of rules. 10070 A style rule. 2650 20522 [@supports rules]( 16723 The [`@viewport`][at] at-rule and [`meta`][meta] element. [at]: [meta]: 29271