csstree

parse(css, {
    onToken(type, start, end, index) {
        if (this.isBlockOpenerTokenType(type)) {
            if (this.getBlockPairTokenIndex(index) === -1) {
                console.warn('No closing pair for', this.getTokenValue(index), this.getRangeLocation(start, end));
            }
        } else if (this.isBlockCloserTokenType(type)) {
            if (this.getBlockPairTokenIndex(index) === -1) {
                console.warn('No opening pair for', this.getTokenValue(index), this.getRangeLocation(start, end));
            }
        }
    }
});

• Feature: represents features like (feature) and (feature: value), fundamental for both @media and @container at-rules
• FeatureRange: represents features in a range context
• FeatureFunction: represents functional features such as @supports's selector() or @container's style()
• Condition: used across all query-like at-rules, encapsulating queries with features and the not, and, and or operators
• GeneralEnclosure: represents the <general-enclosed> production, which caters to unparsed parentheses or functional expressions

Note: All new nodes include a kind property to define the at-rule type. Supported kinds are media, supports, and container

features: {
    supports: { selector() { /* ... */ } },
    container: { style() { /* ... */ } }
}

• Enhanced prelude parsing for complex queries. Parentheses with errors will be parsed as GeneralEnclosed
• Added support for features in a range context, e.g. (width > 100px) or (100px < height < 400px)
• Transitioned from MediaFeature node type to the Feature node type with kind: "media"
• Changed MediaQuery node structure into the following form:

  type MediaQuery = {
      type: "MediaQuery";
      modifier: string | null; // e.g. "not", "only", etc.
      mediaType: string | null; // e.g. "all", "screen", etc.
      condition: Condition | null;
  }
  

• Enhanced prelude parsing for complex queries. Parentheses with errors will be parsed as GeneralEnclosed
• Added support for features in a range context, e.g. (width > 100px) or (100px < height < 400px)
• Added SupportsDeclaration node type to encapsulate a declaration in a query, replacing Parentheses
• Parsing now employs Condition or SupportsDeclaration nodes of kind supports instead of Parentheses
• Added support for the selector() feature via the FeatureFunction node (configured in features.supports.selector)