libs/design/sidebar/src/helper/_variables.scss
// Stacking Context Layers
$daff-sidebar-sidebar-over-z-index: 7;
$daff-sidebar-backdrop-z-index: 6;
$daff-sidebar-sidebar-side-fixed-z-index: 5;
$daff-sidebar-nav-z-index: 4;
$daff-sidebar-content-z-index: 3;
$daff-sidebar-sidebar-under-z-index: 2;
$daff-sidebar-viewport-z-index: 1;