Hiding the Navigation menu while transparent menu is still active.

Hello Support,

I have full browser size image on the homepage and navigation menus are as icons on this picture.

I disabled the navigation menu but I want to show navigation menu when you scroll down.

So how can i activate the transparent menu but disable the navigation menu on the homepage.

The code I used for disabling the navigation menu is :

.page-id-330 nav.main_menu {
display: none!important;
}