diff --git a/packages/happy-dom/src/css/declaration/element-style/CSSStyleDeclarationElementStyle.ts b/packages/happy-dom/src/css/declaration/element-style/CSSStyleDeclarationElementStyle.ts
index c77fb160a..8e981ed8e 100644
--- a/packages/happy-dom/src/css/declaration/element-style/CSSStyleDeclarationElementStyle.ts
+++ b/packages/happy-dom/src/css/declaration/element-style/CSSStyleDeclarationElementStyle.ts
@@ -19,8 +19,8 @@ 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\( *(--[^), ]+), *([^), ]+)\)/;
 const CSS_MEASUREMENT_REGEXP = /[0-9.]+(px|rem|em|vw|vh|%|vmin|vmax|cm|mm|in|pt|pc|Q)/g;
+const CSS_VARIABLE_REGEXP = /var\( *(--[^), ]+)\)|var\( *(--[^), ]+), *(.+)\)/;
 
 type IStyleAndElement = {
 	element: Element | ShadowRoot | Document;
@@ -387,7 +387,7 @@ export default class CSSStyleDeclarationElementStyle {
 	 */
 	private parseCSSVariablesInValue(value: string, cssVariables: { [k: string]: string }): string {
 		let newValue = value;
-		let match;
+		let match: RegExpMatchArray | null;
 
 		while ((match = newValue.match(CSS_VARIABLE_REGEXP)) !== null) {
 			// Fallback value - E.g. var(--my-var, #FFFFFF)
diff --git a/packages/happy-dom/test/window/BrowserWindow.test.ts b/packages/happy-dom/test/window/BrowserWindow.test.ts
index 00a41b0fe..68ea609ae 100644
--- a/packages/happy-dom/test/window/BrowserWindow.test.ts
+++ b/packages/happy-dom/test/window/BrowserWindow.test.ts
@@ -592,11 +592,16 @@ describe('BrowserWindow', () => {
 					color: var(--my-var, var(--my-background, pink));
 
 					--color1: red;
+					--color2: blue;
 					--result1: var(--color1, var(--unknown, var(--unknown, green)));
 					--result2: var(--unknown, var(--color1, var(--unknown, green)));
 					--result3: var(--unknown, var(--unknown, var(--color1, green)));
 					
 					--result4: var(--unknown, var(--unknown, var(--unknown, var(--unknown, white))));
+
+					--result5: var(--color1, var(--color2));
+					--result6: var(--unknown, var(--color2));
+					--result7: var(--unknown, blue);
 				}
 			`;
 
@@ -611,6 +616,57 @@ describe('BrowserWindow', () => {
 			expect(computedStyle.getPropertyValue('--result2')).toBe('red');
 
 			expect(computedStyle.getPropertyValue('--result4')).toBe('white');
+
+			expect(computedStyle.getPropertyValue('--result5')).toBe('red');
+			expect(computedStyle.getPropertyValue('--result6')).toBe('blue');
+			expect(computedStyle.getPropertyValue('--result7')).toBe('blue');
+		});
+
+		it('Returns values defined by a CSS variables when multiple chained variables are used.', () => {
+			const div = document.createElement('div');
+			const divStyle = document.createElement('style');
+
+			divStyle.innerHTML = `
+				div {
+					--my-var1: var(--my-var2);
+					--my-var2: var(--my-var3);
+					--my-var3: var(--my-var4);
+					--my-var4: pink;
+
+
+					--color1: red;
+					--color2: blue;
+					--case1-result1: var(--case1-result2);
+					--case1-result2: var(--case1-result3);
+					--case1-result3: var(--case1-result4);
+					--case1-result4: var(--color1, var(--color2));
+
+					--case2-result1: var(--case2-result2);
+					--case2-result2: var(--case2-result3);
+					--case2-result3: var(--case2-result4);
+					--case2-result4: var(--unknown, var(--color2));
+				}
+			`;
+
+			document.body.appendChild(divStyle);
+			document.body.appendChild(div);
+
+			const computedStyle = window.getComputedStyle(div);
+
+			expect(computedStyle.getPropertyValue('--my-var1')).toBe('pink');
+			expect(computedStyle.getPropertyValue('--my-var2')).toBe('pink');
+			expect(computedStyle.getPropertyValue('--my-var3')).toBe('pink');
+			expect(computedStyle.getPropertyValue('--my-var4')).toBe('pink');
+
+			expect(computedStyle.getPropertyValue('--case1-result1')).toBe('red');
+			expect(computedStyle.getPropertyValue('--case1-result2')).toBe('red');
+			expect(computedStyle.getPropertyValue('--case1-result3')).toBe('red');
+			expect(computedStyle.getPropertyValue('--case1-result4')).toBe('red');
+
+			expect(computedStyle.getPropertyValue('--case2-result1')).toBe('blue');
+			expect(computedStyle.getPropertyValue('--case2-result2')).toBe('blue');
+			expect(computedStyle.getPropertyValue('--case2-result3')).toBe('blue');
+			expect(computedStyle.getPropertyValue('--case2-result4')).toBe('blue');
 		});
 
 		it('Returns a CSSStyleDeclaration object with computed styles containing "rem" and "em" measurement values converted to pixels.', () => {