Slight fix to file server

pico.py

         document = Path(__file__, '..', Path(path).name).resolve()
         if not document.is_file():
             document = Path(__file__, '..', 'pico.html').resolve()
+
+        if document.suffix == '.html':
             content_type = 'text/html; charset=utf-8'
-        elif path.endswith('.js'):
+        elif document.suffix == '.js':
             content_type = 'application/javascript; charset=utf-8'
-        elif path.endswith('.css'):
+        elif document.suffix == '.css':
             content_type = 'text/css; charset=utf-8'
-        elif path.endswith('.svg'):
+        elif document.suffix == '.svg':
             content_type = 'image/svg+xml; charset=utf-8'
         else:
             content_type = 'text/plain; charset=utf-8'
+
         return (
             http.HTTPStatus.OK,
             [('Content-Type', content_type)],