Update app.py

app.py

@@ -312,6 +312,7 @@ class Engine(object):
                 inner_icon_style='color:red;font-size:20px;margin-top:0;',
                 background_color='transparent',
                 border_color='transparent',
+                icon_anchor=(0, 0)
             )
             feature_group = FeatureGroup(name='Ground Truth')
             Marker(