How to force a HTML dropdown menu to open on loading WordPress page

I have an iFrame embedded in my WordPress page (using a custom HTML block) for massage bookings. See [ redundant link removed ]

The iFrame loads with a class, MenuGroup–header–443090, containing the various massages), but this MenuGroup is closed on mobile devices. When clicking the group title or the chevron, it opens and the massages show in a dropdown.

For users who want to book a massage, I find this very distracting. Is there a way to force the group to be opened by default? Using either html, js or css code.

Screenshot with closed menu
Screenshot with opened menu

• This topic was modified 6 years, 1 month ago by cvanbemmel.
• This topic was modified 6 years, 1 month ago by cvanbemmel.
• This topic was modified 6 years, 1 month ago by cvanbemmel.
• This topic was modified 6 years, 1 month ago by Jan Dembowski.

The page I need help with: [log in to see the link]