Why do you want it hidden?

Because we have a pretty big form and it takes a lot of space so we think it might look cleaner if we can remove it from the results page.

Have you thought about using HeaderTabs [0]? Or a collapse template [1]?

[0]: https://www.mediawiki.org/wiki/Extension:Header_Tabs
[1]: https://en.wikipedia.org/wiki/Template:Collapse

Regards,
Tobi

That might work but I'm not sure I can wrap the form in a template as it is generated automatically (and we definitely don't want to hide it when the user is not on the results page).

Oh, my bad. I overlooked the query form part. sry.