sticky burger menu

Hi dear Kriesi-team,

I want to have my burger menu and my search icon to be always fixed at the same time, while the user is scrolling. I got this code from you:

#avia-menu {
display: flex;
flex-direction: column-reverse;
}
@media only screen and (max-width: 990px) {
#top #menu-item-search {
margin-top: -30px;
}
}

I tried to add this
position: fixed;

but than this happens:

View post on imgur.com

How could dI make it sticky again, without destroy the progress on the menu?

Thank you very much

Best,
Veronika