diff --git a/src/css-node.ts b/src/css-node.ts
index b4a4613..03268f8 100644
--- a/src/css-node.ts
+++ b/src/css-node.ts
@@ -37,7 +37,6 @@ import {
 	SUPPORTS_QUERY,
 	LAYER_NAME,
 	PRELUDE_OPERATOR,
-	FLAG_IMPORTANT,
 	FLAG_HAS_ERROR,
 	FLAG_HAS_BLOCK,
 	FLAG_HAS_DECLARATIONS,
@@ -305,10 +304,13 @@ export class CSSNode {
 		return parse_dimension(this.text).unit
 	}
 
-	// Check if this declaration has !important
+	// Check if this declaration has !important (computed on-demand)
 	get is_important(): boolean | null {
 		if (this.type !== DECLARATION) return null
-		return this.arena.has_flag(this.index, FLAG_IMPORTANT)
+		// Check if full declaration text contains ! followed by identifier
+		// This matches !important, !ie (historic), and any other ! + identifier
+		// (value property excludes the ! part, so we check the full text)
+		return /!\s*\w+/.test(this.text)
 	}
 
 	// Check if this has a vendor prefix (computed on-demand)
diff --git a/src/parse.ts b/src/parse.ts
index b375d65..da8fa2e 100644
--- a/src/parse.ts
+++ b/src/parse.ts
@@ -8,7 +8,6 @@ import {
 	DECLARATION,
 	AT_RULE,
 	BLOCK,
-	FLAG_IMPORTANT,
 	FLAG_HAS_BLOCK,
 	FLAG_HAS_DECLARATIONS,
 } from './arena'
@@ -325,7 +324,6 @@ export class Parser {
 		let value_end = value_start
 
 		// Parse value (everything until ';' or '}')
-		let has_important = false
 		let last_end = this.lexer.token_end
 
 		while (!this.is_eof()) {
@@ -346,7 +344,6 @@ export class Parser {
 				// Check if next token is an identifier
 				let next_type = this.lexer.next_token_fast()
 				if (next_type === TOKEN_IDENT) {
-					has_important = true
 					last_end = this.lexer.token_end
 					this.next_token() // Advance to next token after "important"
 					break
@@ -374,11 +371,6 @@ export class Parser {
 			}
 		}
 
-		// Set !important flag if found
-		if (has_important) {
-			this.arena.set_flag(declaration, FLAG_IMPORTANT)
-		}
-
 		// Consume ';' if present
 		if (this.peek_type() === TOKEN_SEMICOLON) {
 			last_end = this.lexer.token_end