diff --git a/test/helpers.js b/test/helpers.js
index 1382af0691..f118a818f7 100644
--- a/test/helpers.js
+++ b/test/helpers.js
@@ -102,7 +102,7 @@ function cleanChildren(node) {
 	});
 
 	// recurse
-	[...node.childNodes].forEach((child) => {
+	for (let child of node.childNodes) {
 		if (child.nodeType === 3) {
 			// text
 			if (
@@ -130,7 +130,7 @@ function cleanChildren(node) {
 		}
 
 		previous = child;
-	});
+	}
 
 	// collapse whitespace
 	if (node.firstChild && node.firstChild.nodeType === 3) {
diff --git a/test/runtime-puppeteer/assert.js b/test/runtime-puppeteer/assert.js
index e4d6f02f33..32e14b6830 100644
--- a/test/runtime-puppeteer/assert.js
+++ b/test/runtime-puppeteer/assert.js
@@ -43,8 +43,23 @@ function normalizeHtml(window, html) {
 			.replace(/<!--.*?-->/g, '')
 			.replace(/>[\s\r\n]+</g, '><')
 			.trim();
+
+		cleanStyle(node);
+
 		return node.innerHTML.replace(/<\/?noscript\/?>/g, '');
 	} catch (err) {
 		throw new Error(`Failed to normalize HTML:\n${html}`);
 	}
 }
+
+function cleanStyle(node) {
+	if (node.nodeType === 1) {
+		if (node.hasAttribute('style')) {
+			node.style = node.style.cssText;
+		}
+
+		for (const child of node.childNodes) {
+			cleanStyle(child);
+		}
+	}
+}