I've tried to create a demo campaign page without choosing any options in the customizer.

https://k8s.p4.greenpeace.org/campaigns/campaign/default-template-demo/

The issue is that the page should use the default Planet4 theme since there was no "override" selected. Default header fonts, default button colors, etc should be used. Instead the campaign page took the header fonts, button colors from the Antarctica styleguide. This is a new bug, earlier versions of the customizer worked correctly.

The correct/expected behaviour: when no customizer options are selected (especially no template selected in the Campaign Template dropdown on the right side in the Edit page area) the page should use the default P4 theme.