There's a grey bar under the header on all templates (but the Climate Emergency version) that is not part of the design. I think it's coming from the EN Form block actually. It should be removed.

(Might be related but there is a customizer option called "Navigation bottom border" that is apparently not working)

Some example pages where it's present:

https://k8s.p4.greenpeace.org/nikosdev/campaign/all-blocks-demo-plastics/