update musicxml viz

app.py

@@ -67,7 +67,11 @@ def render_musicxml_via_verovio_api(musicxml_path: Path) -> str:
     try:
         svg = response.json()["svg"]
         svg_b64 = base64.b64encode(svg.encode("utf-8")).decode("utf-8")
-        html = f'<img src="data:image/svg+xml;base64,{svg_b64}" style="width:100%; max-height:600px;" />'
+        html = f'''
+        <div style="background-color: white; padding: 10px; border-radius: 8px;">
+            <img src="data:image/svg+xml;base64,{svg_b64}" style="width:100%; max-height:600px;" />
+        </div>
+        '''
         return html
     except Exception as e:
         return f"⚠️ SVG 解析失败：{e}"