Docs nav offset

[andreasvirkus]

Noticed a minor visual inconsistency that can sometimes be annoying when browsing around the docs (e.g. it blocks the table of contents on the left), since the docs do not display the Support Ukraine banner, there's a redundant 60px offset for the navbar. Same applies for the Support page.

I'm willing to PR this, but should we... a) include the support banner for the default layout as well b) make the .fixedHeaderContainer class's top: 60px style conditional and only apply it within home's {% include nav.html %}

[xavierd]

cc: @dmitryvinn, I believe you added the banner. Any opinion on adding it for all the pages?