Interestingly, it stays closed by default for me (on mobile/small screen sizes).
Which devices are you experiencing this with and can you provide a URL to the site?
I use iPhone.
This is link: Calendar
Apologies, I do see it now.
This may well be a bug and it seems to happen if you have only enabled a single event view in Events → Settings → Display (activate two different views, such as month and list, and the problem disappears).
I’ll be sure to log this and we’ll update you as soon as we have some news to share.
Thanks for reporting this!
Oh! Thanks for the tip! Yes, it is now more compact.