AtRulePrelude
data class AtRulePrelude(val location: CssLocation, val value: String) : CssComponentValueNode(source)
Represents the prelude of an at-rule in a CSS stylesheet.
The prelude is the part of the at-rule that comes before the block, and typically contains the rule's name and any parameters.
For example, in the at-rule @media screen and (max-width: 600px), the prelude is screen and (max-width: 600px).