Fix imports

app.py

@@ -6,6 +6,7 @@ import vizro.models as vm
 from chart_groups import ALL_CHART_GROUP, CHART_GROUPS, ChartGroup, IncompletePage
 from custom_components import FlexContainer, Markdown
 from vizro import Vizro
+from dash import html
 
 
 def make_chart_card(page: Union[vm.Page, IncompletePage]) -> vm.Card: