diff --git a/ext/js/dom/sandbox/css-style-applier.js b/ext/js/dom/sandbox/css-style-applier.js
index a1c33822e7..ea3f1a28e7 100644
--- a/ext/js/dom/sandbox/css-style-applier.js
+++ b/ext/js/dom/sandbox/css-style-applier.js
@@ -16,7 +16,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-import {fetchJson} from '../../core/fetch-utilities.js';
+import {readResponseJson} from '../../core/json.js';
 
 /**
  * This class is used to apply CSS styles to elements using a consistent method
@@ -48,7 +48,7 @@ export class CssStyleApplier {
         /** @type {import('css-style-applier').RawStyleData} */
         let rawData = [];
         try {
-            rawData = await fetchJson(this._styleDataUrl);
+            rawData = await this._fetchJsonAsset(this._styleDataUrl);
         } catch (e) {
             // eslint-disable-next-line no-console
             console.error(e);
@@ -98,6 +98,28 @@ export class CssStyleApplier {
 
     // Private
 
+    /**
+     * Fetches and parses a JSON file.
+     * @template [T=unknown]
+     * @param {string} url The URL to the file.
+     * @returns {Promise<T>} A JSON object.
+     * @throws {Error} An error is thrown if the fetch fails.
+     */
+    async _fetchJsonAsset(url) {
+        const response = await fetch(url, {
+            method: 'GET',
+            mode: 'no-cors',
+            cache: 'default',
+            credentials: 'omit',
+            redirect: 'follow',
+            referrerPolicy: 'no-referrer'
+        });
+        if (!response.ok) {
+            throw new Error(`Failed to fetch ${url}: ${response.status}`);
+        }
+        return await readResponseJson(response);
+    }
+
     /**
      * Gets an array of candidate CSS rules which might match a specific class.
      * @param {string} className A whitespace-separated list of classes.