{{!-- ========================================================================== OFF-CANVAS MENU (usable at all breakpoints, not just mobile) The Bootstrap offcanvas only slides in completely from the right below .site-header (header stays visible/usable). Level 1 (main items) always stays in place; opening a main item slides its level-2 panel via transform from the right OVER level 1 (and vice versa via the back button, which also shows the main item's name). Within level 2, the groups can be opened as an accordion (level 3, no further sliding). Opacity always stays 1, only transform is animated. The complete logic lives in main/offcanvas-menu.js. ========================================================================== --}}
{{!-- A single nav landmark for the entire drilldown (levels 1-3), not one per level: level 1 (below, now a div) gets [inert] when a sub-level opens and disappears from the a11y tree – if the landmark only wrapped level 1, it would disappear along with it during the drilldown, even though the user is still within the same menu. --}}