/* ─────────────────────────────────────────────
   Z-INDEX — stacking order by role
   Named layers, spaced by 100 so you can slot
   values in between if ever needed. Always use a
   token, never a raw z-index in component code.
   ───────────────────────────────────────────── */
:root {
  --z-base:     0;
  --z-dropdown: 100;   /* menus, selects */
  --z-sticky:   200;   /* sticky headers, toolbars */
  --z-overlay:  300;   /* dimming backdrop */
  --z-modal:    400;   /* dialogs, sheets */
  --z-popover:  500;   /* popovers, tooltips above modals */
  --z-toast:    600;   /* notifications — always on top */
}