Name Description Size A [`@container`][container] rule. [container]: 21244 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`. 11281 292 The [`@font-feature-values`][font-feature-values] at-rule. [font-feature-values]: 18224 The [`@font-palette-values`][font-palette-values] at-rule. [font-palette-values]: 9350 The [`@import`][import] at-rule. [import]: 9469 Keyframes: 23965 A [`@layer`][layer] rule. [layer]: 7096 The stylesheet loader is the abstraction used to trigger network requests for `@import` rules. 1161 A [`@margin`][margin] rule. [margin]: 6360 An [`@media`][media] rule. [media]: 2631 Style sheets and their CSS rules. 21930 The `@namespace` at-rule. 1433 [CSS cascade origins]( 6985 A [`@page`][page] rule. [page]: 12537 293 A list of CSS rules. 5764 Parsing of the stylesheet contents. 39117 An iterator over a list of rules. 10079 A style rule. 3655 19228 [@supports rules]( 14876