refactor: Improve type safety and remove unnecessary type annotation

Author: mdevils

src/parser.ts

@@ -90,7 +90,7 @@ export function createParser(
     if (syntaxDefinition.baseSyntax) {
         syntaxDefinition = extendSyntaxDefinition(cssSyntaxDefinitions[syntaxDefinition.baseSyntax], syntaxDefinition);
     }
-    
+
     // Apply additional features if specified
     if (features && features.length > 0) {
         for (const feature of features) {

src/syntax-definitions.ts

@@ -4,13 +4,6 @@ export type PseudoClassType = Exclude<'NoArgument' | AstPseudoClassArgument['typ
 export type PseudoElementType = Exclude<'NoArgument' | AstPseudoElementArgument['type'], 'Substitution'>;
 export type CssLevel = 'css1' | 'css2' | 'css3' | 'selectors-3' | 'selectors-4' | 'latest' | 'progressive';
 
-/**
- * CSS Feature module name.
- * @example 'css-position-3'
- * @example 'css-scoping-1'
- */
-export type CssFeature = string;
-
 /**
  * CSS Selector Syntax Definition can be used to define custom CSS selector parsing rules.
  */
@@ -415,12 +408,12 @@ export const cssSyntaxDefinitions: Record<CssLevel, SyntaxDefinition> = {
 /**
  * CSS Feature modules with their syntax definitions.
  * These can be used to extend the parser with specific CSS features.
- * 
+ *
  * @example
  * // Using the css-position-3 feature
  * createParser({ features: ['css-position-3'] })
  */
-export const cssFeatures: Record<string, SyntaxDefinition> = {
+export const cssFeatures = {
     'css-position-3': {
         pseudoClasses: {
             definitions: {
@@ -446,4 +439,11 @@ export const cssFeatures: Record<string, SyntaxDefinition> = {
             definitions: ['slotted']
         }
     }
-};
+} satisfies Record<string, SyntaxDefinition>;
+
+/**
+ * CSS Feature module name.
+ * @example 'css-position-3'
+ * @example 'css-scoping-1'
+ */
+export type CssFeature = keyof typeof cssFeatures;