Header padding inconsistency

Hi

I am having problems with padding in my website header.

On some pages the padding is showing correctly:https://staging1.courses.idas.org.uk/about-idas/
[img]https://i.imgur.com/Ha1apsZ.png[/img]

And on others an extra bit of padding is being added and I can't work out why.
https://staging1.courses.idas.org.uk/
[img]https://i.imgur.com/swK3Jho.jpg[/img]

I'd really appreciate any help you can give me to solve this. I'm tearing my hair out!

Thanks very much,
Helen