diff --git a/src/components/ViewerPanel.tsx b/src/components/ViewerPanel.tsx
index 2003c95..ad153cb 100644
--- a/src/components/ViewerPanel.tsx
+++ b/src/components/ViewerPanel.tsx
@@ -47,6 +47,7 @@ export default function ViewerPanel({className, style}: {className?: string, sty
           }}>
       <model-viewer
         orientation="0deg -90deg 0deg"
+        class="main-viewer"
         src={state.output?.displayFileURL ?? state.output?.outFileURL ?? ''}
         style={{
           width: '100%',
diff --git a/tests/e2e.test.js b/tests/e2e.test.js
index f51f092..d3152b2 100644
--- a/tests/e2e.test.js
+++ b/tests/e2e.test.js
@@ -10,6 +10,11 @@ describe('e2e', () => {
     page.goto(url);
     await page.waitForSelector('model-viewer');
 
+    await page.waitForFunction(() => {
+      const viewer = document.querySelector('model-viewer.main-viewer');
+      return viewer && viewer.src !== '';
+    });
+
     console.log('Messages:', JSON.stringify(messages, null, 2));
     
     const errors = messages.filter(msg => msg.type === 'error');