/* Drawer geometry uses the shared density tokens; only the body scrolls. */
#chapters-dialog { width: min(400px, calc(100vw - var(--space-4))); height: 100dvh; max-height: 100dvh; margin: 0 0 0 auto; padding: 0; overflow: hidden; border: 0; border-left: 1px solid var(--line); border-radius: 0; background: var(--panel); color: var(--text); }
#chapters-dialog[open] { display: flex; flex-direction: column; }
#chapters-dialog .chapters-heading { flex: none; display: flex; align-items: center; gap: var(--space-3); margin: 0; padding: max(var(--space-4), env(safe-area-inset-top)) var(--page-gutter) var(--space-3); border-bottom: 1px solid var(--line); background: var(--panel); }
#chapters-dialog .chapters-heading > div { flex: 1; min-width: 0; }
#chapters-dialog .chapters-heading h2 { margin: var(--space-1) 0 0; font-size: 21px; font-weight: 600; line-height: 1.4; }
#chapters-close { flex: none; display: grid; place-items: center; min-width: 44px; min-height: 44px; border: 1px solid var(--line); border-radius: 8px; }
.mobile-nav-search-label { flex: none; position: relative; display: flex; align-items: center; gap: var(--space-2); margin: var(--space-3) var(--page-gutter); padding-inline: var(--space-3); border: 1px solid var(--line); border-radius: 8px; background: var(--bg); }
.mobile-nav-search-label > .ui-icon { flex: none; width: 18px; height: 18px; }
#mobile-nav-search { width: 100%; min-width: 0; min-height: 44px; padding: var(--space-2) 0; border: 0; background: transparent; color: var(--text); font: inherit; font-size: 16px; }
#mobile-nav-search::placeholder { color: var(--muted); opacity: 1; }
.mobile-drawer-body { flex: 1; min-height: 0; overflow-y: auto; overflow-x: hidden; padding: 0 var(--page-gutter) max(var(--space-4), env(safe-area-inset-bottom)); overscroll-behavior: contain; scrollbar-width: thin; scrollbar-color: var(--line) transparent; }
.mobile-drawer-body [hidden] { display: none !important; }
.mobile-nav-quick, .mobile-nav-sections { display: grid; gap: var(--space-1); }
.mobile-nav-quick { padding-bottom: var(--space-3); margin-bottom: var(--space-3); border-bottom: 1px solid var(--line); }
.mobile-drawer-body :is(.mobile-nav-link, summary) { display: flex; align-items: center; gap: var(--space-3); min-height: 44px; padding: var(--space-2); margin: 0; border: 1px solid transparent; border-radius: 8px; background: transparent; color: var(--text); font-size: 14px; line-height: 1.5; text-decoration: none; list-style: none; cursor: pointer; }
.mobile-drawer-body summary::-webkit-details-marker { display: none; }
.mobile-drawer-body :is(a,summary):hover { background: var(--raised); }
.mobile-drawer-body :is(a,summary):focus-visible, #chapters-dialog :is(button,input):focus-visible { outline: 2px solid var(--accent); outline-offset: -2px; }
.mobile-drawer-body .mobile-nav-icon { flex: none; display: grid; place-items: center; width: 28px; height: 28px; border: 1px solid var(--line); border-radius: 7px; }
.mobile-drawer-body .mobile-nav-icon .ui-icon { display: block; width: 17px; height: 17px; }
.mobile-nav-label { flex: 1; min-width: 0; overflow-wrap: anywhere; }
.mobile-nav-count { flex: none; min-width: 20px; color: var(--muted); font-size: 11px; text-align: right; font-variant-numeric: tabular-nums; }
.mobile-nav-chevron { flex: none; color: var(--accent); font-size: 20px; line-height: 1; }
.mobile-nav-section[open] > summary > .mobile-nav-chevron, .mobile-nav-track[open] > summary > .mobile-nav-chevron { transform: rotate(90deg); }
.mobile-nav-section.is-current > summary, .mobile-nav-track.is-current > summary { font-weight: 600; border-color: var(--line); background: var(--raised); }
.mobile-section-content { display: grid; gap: var(--space-1); padding: var(--space-1) 0 var(--space-2) var(--space-2); }
.mobile-section-content > .mobile-nav-link, .mobile-track-content > .mobile-nav-link { font-size: 12px; color: var(--muted); }
.mobile-track-content { padding: var(--space-1) 0 var(--space-2) var(--space-2); }
.mobile-lesson-list { border-left: 1px solid var(--line); margin-left: var(--space-2); padding-left: var(--space-1); }
.mobile-drawer-body .mobile-lesson-link { display: flex; align-items: center; gap: var(--space-2); min-height: 44px; padding: var(--space-2); margin: 0; border: 1px solid transparent; border-radius: 6px; color: var(--muted); font-size: 13px; line-height: 1.5; text-decoration: none; }
.mobile-drawer-body .mobile-lesson-code { flex: none; display: grid; place-items: center; width: 34px; min-height: 28px; margin: 0; padding: 0; border-radius: 4px; font-size: 10px; font-variant-numeric: tabular-nums; }
.mobile-lesson-title { min-width: 0; overflow-wrap: anywhere; }
.mobile-drawer-body a[aria-current='page'] { color: var(--text); background: var(--raised); border-color: var(--line); box-shadow: inset 2px 0 var(--accent); }
.mobile-nav-empty { padding: var(--space-4) var(--space-2); margin: 0; color: var(--muted); font-size: 14px; line-height: 1.6; }
@media (max-width: 360px) { #chapters-dialog { width: calc(100vw - var(--space-2)); } .mobile-drawer-body :is(.mobile-nav-link, summary) { gap: var(--space-2); } }
@media (prefers-reduced-motion: reduce) { #chapters-dialog, #chapters-dialog * { animation: none !important; transition: none !important; scroll-behavior: auto !important; } }