Sticky Header not work on mobile devises

Sticky Header don’t work on mobile and tablet. I read this thread but this solution didn’t work for me.
Perhaps a problem with devices with a screen resolution of less than 800?
How to solve this problem?
Devices that do not work are highlighted in red here.

My “Additional CSS” code:

.page-id-257 .wpforms-form button[type=submit] {
    background-color: #000 !important;
    border-color: #000 !important;
    color: #fff !important;
}
 
.page-id-257 .wpforms-form button[type=submit]:hover {
    background-color: #000 !important;
}
.page-id-257 .wpforms-form input,
.page-id-257 .wpforms-form textarea {
	border-color: #000 !important;
}

.sticky-header-active .mobile-header {
  position: sticky;
  top: 0;
}

• This topic was modified 3 years, 1 month ago by ko1obok.

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