add download button

app.py

@@ -60,8 +60,24 @@ def molecule(input_pdb):
         </script>
         </body></html>"""
     )
+    dw_script = """
+        <script type="text/javascript" >
+            function download(filename, text) /{
+                var element = document.createElement('a');
+                element.setAttribute('href', 'data:text/plain;charset=utf-8,' + encodeURIComponent(text));
+                element.setAttribute('download', filename);
 
-    return f"""<iframe style="width: 100%; height: 600px" name="result" allow="midi; geolocation; microphone; camera; 
+                element.style.display = 'none';
+                document.body.appendChild(element);
+
+                element.click();
+
+                document.body.removeChild(element);
+                /}
+        </script>
+    """
+
+    return dw_scriipt + f"""<iframe style="width: 100%; height: 600px" name="result" allow="midi; geolocation; microphone; camera; 
     display-capture; encrypted-media;" sandbox="allow-modals allow-forms 
     allow-scripts allow-same-origin allow-popups 
     allow-top-navigation-by-user-activation allow-downloads" allowfullscreen=""