Strange styling issue with CF7

Hello reader,

I’m currently working on a website for a car garage here in The Netherlands. I have a very strange problem and haven’t been able to solve it for days. When adding CF7 widget (or by text with the form url) it looks great and exactly how I want to. But in live modus, the styling of the areas below CF7 look very strange.

Screenshot 1 & 2:
Display in preview mode as it should. Please see: http://staging.autodemontagenijmegen.nl/wp-content/uploads/2023/10/WP1.png and http://staging.autodemontagenijmegen.nl/wp-content/uploads/2023/10/WP2.png

Screenshot 2:
How it looks in live modus. Please see: http://staging.autodemontagenijmegen.nl/wp-content/uploads/2023/10/WP3.png

Screenshot 3:
HTML I used for syling the form. Please see: http://staging.autodemontagenijmegen.nl/wp-content/uploads/2023/10/WP4.png

And another problem (but not as important as the other problem): I can’t adjust the styling of the buttons. This remains in the theme default.

What do I wrong? It’s very frustrating and I’m stuck. Thank you very much in advance!