I see what you mean. The following CSS might need a modification, but try adding this now:
@media all and (min-width: 900px) {
.site-header,
.sidebar-primary {
position: fixed;
z-index: 9;
width: 100%;
top: 0;
left: 0;
background: white;
}
.admin-bar .site-header {
top: 32px;
}
.sidebar-primary {
top: 126px;
}
.admin-bar .sidebar-primary {
top: 158px;
}
}
The 126px value in this part may need to be adjusted up/down to line up right on your site:
.sidebar-primary {
top: 126px;
}
And then this part should be the same exact value plus 32:
.admin-bar .sidebar-primary {
top: 158px;
}
That’s so it moves down the height of the admin toolbar when you’re logged in and viewing the site.