Now add this CSS:
.main-navigation:not(.slideout-navigation) .main-nav {
flex: 1;
}
.main-navigation:not(.slideout-navigation) .main-nav > ul {
display: flex;
}
.main-navigation:not(.slideout-navigation) .main-nav ul li.search-item {
order: -1;
}
.main-navigation:not(.slideout-navigation) .main-nav ul li.slideout-toggle {
margin-right: auto;
}
#site-navigation .navigation-branding {
position: absolute;
left: 80px;
}