CSS rule that breaks the buttons in Google Maps

Hi, I use WP 5.0.2 an in my WP backend. The buttons from Google-Maps on the right side of all maps are ok. If I look at the user website there are wrong buttons. With other words the buttons in the WP backend are different from the users website.

Here is an example of the wrong buttons on Google maps:

https://oldtimer-veranstaltung.de/kalender/termine/150er-rallye-2/

As attached you can see the google-map in the WP-Backend.

This happened in Firefox, Safari, Google Chrome and Opera.

I found this CSS rule that breaks the buttons:

.em-location-map img, .em-locations-map img, #em-map img {margin:0 !important}

But this CSS code doesn’t come from the used theme.

Do you have a solution for the wrong button in Google Maps?

Thanks for help
Michael Held

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