CSS at-rules
At-rules are CSS statements that instruct CSS how to behave. They are used to group and structure style rules and other at-rules, declare style information not directly associated with selected content, and manage syntactic constructs such as imports and namespaces keyword mappings. They begin with an at-sign, @ (U+0040 COMMERCIAL AT), followed by an identifier.
Index of at-rules and at-rule descriptors
@charset@color-profile@container@counter-style@custom-media@document@font-face@font-feature-values@font-palette-values@function@import@keyframes@layer@media(see list of media features in the next section)@namespace@page@position-try@property@scope@starting-style@supports@view-transition