Update background.js

background.js

@@ -0,0 +1,5 @@
+document.addEventListener('DOMContentLoaded', () => {
+    const bgImageDiv = document.querySelector('.bg-image');
+    const unsplashURL = 'https://source.unsplash.com/1600x900/?developer';
+    bgImageDiv.style.backgroundImage = `url(${unsplashURL})`;
+});