Added generic html properties function to dash wrapper class and template that uses it

Author: Mark Gibbs

django_plotly_dash/dash_wrapper.py

@@ -302,7 +302,7 @@ def flask_app(self):
         return self._flask_app
 
     def base_url(self):
-        'Base url of this omponent'
+        'Base url of this component'
         return self._base_pathname
 
     def app_context(self, *args, **kwargs):
@@ -412,3 +412,12 @@ def dispatch_with_args(self, body, argMap):
             da.update_current_state(output['id'], output['property'], value)
 
         return res
+
+    def extra_html_properties(self):
+        '''
+        Return extra html properties to allow individual apps to be styled separately.
+
+        The content returned from this function is injected unescaped into templates.
+        '''
+
+        return 'class="django-plotly-dash django-plotly-dash-iframe"'

django_plotly_dash/templates/django_plotly_dash/plotly_app.html

@@ -1,3 +1,3 @@
-<div style="{{dstyle}}">
+<div style="{{dstyle}}" {%autoescape off%}{{app.extra_html_properties}}{%endautoescape%}>
   <iframe src="{{app.base_url}}" style="{{istyle}}"frameborder="{{fbs}}"></iframe>
 </div>