Problem with active field in WPForms

Hi, I’ve inserted a WPForm in a Hestia theme, but I’ve one problem.
When I’m not in fields, everything goes fine, with no background in the fields. But when I’m writing in some of the fields, the background turns purple, which is something I haven’t set up.
I’ve tried adding some CSS additional code but that doesn’t solve the problem. Could someone please help me?
Find attached two screenshots of my problem.
Not writing in the field
Writing in the field

Thanks a lot in advance ??