Merge pull request #1312 from capricorn86/1308-if-multiple-custom-pro…

…perty-fallbacks-occur-getpropertyvalue-returns-an-empty-string

chore: [#1308] Fixes problem with last implementation for parsing CSS…

packages/happy-dom/src/css/declaration/element-style/CSSStyleDeclarationElementStyle.ts

@@ -19,7 +19,7 @@ import CSSMeasurementConverter from '../measurement-converter/CSSMeasurementConv
 import MediaQueryList from '../../../match-media/MediaQueryList.js';
 import WindowBrowserSettingsReader from '../../../window/WindowBrowserSettingsReader.js';
 
-const CSS_VARIABLE_REGEXP = /var\( *(--[^), ]+)\)|var\( *(--[^), ]+), *([^), ]+)\)/g;
+const CSS_VARIABLE_REGEXP = /var\( *(--[^), ]+)\)|var\( *(--[^), ]+), *([^), ]+)\)/;
 const CSS_MEASUREMENT_REGEXP = /[0-9.]+(px|rem|em|vw|vh|%|vmin|vmax|cm|mm|in|pt|pc|Q)/g;
 
 type IStyleAndElement = {
@@ -364,11 +364,10 @@ export default class CSSStyleDeclarationElementStyle {
 	 * @returns CSS value.
 	 */
 	private parseCSSVariablesInValue(value: string, cssVariables: { [k: string]: string }): string {
-		const regexp = new RegExp(CSS_VARIABLE_REGEXP);
 		let newValue = value;
 		let match;
 
-		while ((match = regexp.exec(newValue)) !== null) {
+		while ((match = newValue.match(CSS_VARIABLE_REGEXP)) !== null) {
 			// Fallback value - E.g. var(--my-var, #FFFFFF)
 			if (match[2] !== undefined) {
 				newValue = newValue.replace(match[0], cssVariables[match[2]] || match[3]);