How to hide the DIVI secondary menu before scroll

You can remove the secondary menubar before scrolling with this CSS snippet below. This will make the primary menu bar visible before scrolling, but the secondary bar only available when scrolled.

The custom CSS code is:

.et_fixed_nav #top-header {
visibility: hidden;
}

.et_fixed_nav #top-header.et-fixed-header {
visibility: visible;
}