/* ============================================================================
   Shell — application frame: navigation drawer, navigation rail, top app bar,
   navigation bar, search view, calculator side sheet, snackbar, lightbox.
   Geometry/colour from the M3 spec (spec/generated/SPEC_CHEATSHEET.md):
   drawer 360dp · rail 80dp · app bar 64dp · nav bar 80dp · side sheet 256dp.
   ========================================================================== */

/* Legacy-layer neutralisation: properties the old stylesheet sets on these
   shared classes must not leak into the M3 shell. shell.css is loaded after
   legacy.css, so higher specificity replaces the old !important. */
.shell .main-column { margin: 0; }
.shell .sidebar { padding: var(--layout-safe-top) 0 0; }
.shell .topbar { justify-content: flex-start; }

/* ---------- frame ---------- */
.shell {
  min-height: 100vh;
  min-height: 100dvh;
  display: block;
  background: var(--md-sys-color-surface);
}

.main-column {
  display: flex;
  flex-direction: column;
  min-width: 0;
  min-height: 100vh;
  min-height: 100dvh;
  padding-left: 0;
  transition: padding-left var(--md-sys-motion-duration-medium2)
    var(--md-sys-motion-easing-standard);
}

#app {
  flex: 1 0 auto;
  width: 100%;
  max-width: var(--layout-content-max);
  margin: 0 auto;
  padding: var(--md-sys-measurement-space250) var(--layout-gutter) var(--md-sys-measurement-space600);
  scroll-margin-top: calc(var(--layout-topbar-height) + var(--layout-safe-top) +
      var(--md-sys-measurement-space200));
}

/* Page transition: single subtle fade per destination (M3 emphasized decelerate). */
#app.view-enter > * {
  animation: m3-page-enter var(--md-sys-motion-duration-medium2)
    var(--md-sys-motion-easing-emphasized-decelerate) both;
}
@keyframes m3-page-enter {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: none; }
}

/* ---------------------------------------------------------------------------
   Navigation drawer — standard 360dp on expanded+ (≥840px), modal below.
   --------------------------------------------------------------------------- */
.sidebar {
  position: fixed;
  inset: 0 auto 0 0;
  z-index: var(--z-drawer);
  width: var(--md-comp-nav-drawer-container-width);
  display: flex;
  flex-direction: column;
  background: var(--md-sys-color-surface);
  border-right: 0;
  transform: translateX(-100%);
  transition: transform var(--md-sys-motion-duration-medium2)
    var(--md-sys-motion-easing-emphasized-decelerate);
  overscroll-behavior: contain;
}
body.menu-open .sidebar {
  transform: translateX(0);
  background: var(--md-sys-color-surface-container-low);
  border-radius: var(--md-sys-shape-corner-large-end);
  box-shadow: var(--md-sys-elevation-level1);
}

.sidebar-head {
  display: flex;
  align-items: center;
  gap: var(--md-sys-measurement-space100);
  padding: var(--md-sys-measurement-space150) var(--md-sys-measurement-space150)
    var(--md-sys-measurement-space100) var(--md-sys-measurement-space200);
  flex-shrink: 0;
}
.brand {
  display: flex;
  align-items: center;
  gap: var(--md-sys-measurement-space150);
  min-width: 0;
  flex: 1 1 auto;
  min-height: 48px;
  padding: var(--md-sys-measurement-space50);
  margin: 0;
  border: 0;
  background: transparent;
  border-radius: var(--md-sys-shape-corner-full);
  text-align: left;
  color: var(--md-sys-color-on-surface);
  transition: background-color var(--md-sys-motion-duration-short3)
    var(--md-sys-motion-easing-standard);
}
.brand:hover { background: color-mix(in srgb, var(--md-sys-color-on-surface) 8%, transparent); }
.brand-mark {
  flex-shrink: 0;
  display: inline-grid;
  place-items: center;
  width: 40px;
  height: 40px;
  border-radius: var(--md-sys-shape-corner-medium);
  background: var(--md-sys-color-primary-container);
  color: var(--md-sys-color-on-primary-container);
}
.brand-copy { display: flex; flex-direction: column; min-width: 0; line-height: 1.25; }
.brand-copy strong {
  font-size: var(--md-sys-typescale-title-medium-size);
  line-height: var(--md-sys-typescale-title-medium-line);
  font-weight: var(--md-sys-typescale-title-medium-weight);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.brand-copy small {
  font-size: var(--md-sys-typescale-body-small-size);
  color: var(--md-sys-color-on-surface-variant);
  white-space: nowrap;
}
.sidebar .drawer-close {
  flex-shrink: 0;
  display: none;
  width: var(--md-comp-icon-button-target-size);
  height: var(--md-comp-icon-button-target-size);
  padding: calc((var(--md-comp-icon-button-target-size) -
        var(--md-comp-icon-button-container-height)) / 2);
  background-clip: content-box;
}

.sidebar-scroll {
  flex: 1 1 auto;
  min-height: 0;
  overflow-y: auto;
  overscroll-behavior: contain;
  padding: var(--md-sys-measurement-space50) var(--md-sys-measurement-space150)
    var(--md-sys-measurement-space200);
}

/* Subject switcher card */
.sidebar-subject-card {
  display: flex;
  flex-direction: column;
  gap: var(--md-sys-measurement-space100);
  padding: var(--md-sys-measurement-space100);
  margin: var(--md-sys-measurement-space50) 0 var(--md-sys-measurement-space100);
  border-radius: var(--md-sys-shape-corner-large);
  background: var(--md-sys-color-surface-container-low);
  border: 1px solid var(--md-sys-color-outline-variant);
}
.subject-picker {
  display: flex;
  align-items: center;
  gap: var(--md-sys-measurement-space150);
  width: 100%;
  min-height: 56px;
  padding: var(--md-sys-measurement-space50) var(--md-sys-measurement-space100);
  border: 0;
  border-radius: var(--md-sys-shape-corner-medium);
  background: transparent;
  text-align: left;
  color: var(--md-sys-color-on-surface);
  transition: background-color var(--md-sys-motion-duration-short3)
    var(--md-sys-motion-easing-standard);
}
.subject-picker:hover { background: color-mix(in srgb, var(--md-sys-color-on-surface) 8%, transparent); }
.subj-badge {
  flex-shrink: 0;
  display: inline-grid;
  place-items: center;
  width: 40px;
  height: 40px;
  border-radius: var(--md-sys-shape-corner-full);
  /* subject colour roles are set by [data-subject] on <html> in tokens.css */
  background: var(--subject-accent);
  color: var(--subject-on-accent);
  font-size: var(--md-sys-typescale-label-large-size);
  font-weight: var(--md-sys-typescale-label-large-weight);
  letter-spacing: 0.02em;
}
.subj-info { display: flex; flex-direction: column; min-width: 0; flex: 1 1 auto; line-height: 1.3; }
.subj-label {
  font-size: var(--md-sys-typescale-label-small-size);
  font-weight: var(--md-sys-typescale-label-small-weight);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--md-sys-color-on-surface-variant);
}
.subj-name {
  font-size: var(--md-sys-typescale-title-small-size);
  font-weight: var(--md-sys-typescale-title-small-weight);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.subj-action-icon { color: var(--md-sys-color-on-surface-variant); flex-shrink: 0; }

/* Quick subject switch — M3 filter chips: 32dp visual chip (8dp corner,
   outline when unselected, secondary-container when selected) inside a
   48dp touch target (8dp transparent band above and below the chip). */
/* Subject quick switch — M3 connected segmented control (single outline,
   selected segment = secondary-container; no per-subject border noise). */
.subject-quick-switch {
  display: flex;
  align-items: stretch;
  gap: 0;
  padding: 0;
  overflow: visible;
  border: 1px solid var(--md-sys-color-outline-variant);
  border-radius: var(--md-sys-shape-corner-full);
  background: var(--md-sys-color-surface);
}
.subject-quick-btn {
  position: relative;
  flex: 1 1 0;
  min-width: 0;
  isolation: isolate;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--md-sys-measurement-space75);
  min-height: 40px;
  padding: 0 var(--md-sys-measurement-space125);
  border: 0;
  border-radius: 0;
  background: transparent;
  color: var(--md-sys-color-on-surface-variant);
  font-size: var(--md-sys-typescale-label-large-size);
  line-height: var(--md-sys-typescale-label-large-line);
  font-weight: var(--md-sys-typescale-label-large-weight);
  white-space: nowrap;
  overflow: hidden;
  transition: background-color var(--md-sys-motion-duration-short3)
      var(--md-sys-motion-easing-standard),
    color var(--md-sys-motion-duration-short3) var(--md-sys-motion-easing-standard);
}
.subject-quick-btn:first-child { border-radius: var(--md-sys-shape-corner-full) 0 0 var(--md-sys-shape-corner-full); }
.subject-quick-btn:last-child { border-radius: 0 var(--md-sys-shape-corner-full) var(--md-sys-shape-corner-full) 0; }
.subject-quick-btn + .subject-quick-btn { border-left: 1px solid var(--md-sys-color-outline-variant); }
/* 48dp touch target without changing the 40dp visual segment */
.subject-quick-btn::before {
  content: "";
  position: absolute;
  inset: -4px 0;
  min-height: var(--md-comp-target-size);
  border-radius: var(--md-sys-shape-corner-full);
}
.subject-quick-btn:hover { background: color-mix(in srgb, var(--md-sys-color-on-surface) 8%, transparent); }
.subject-quick-btn.active,
.subject-quick-btn[aria-pressed="true"] {
  background: var(--md-sys-color-secondary-container);
  color: var(--md-sys-color-on-secondary-container);
}
.subject-quick-btn.active + .subject-quick-btn,
.subject-quick-btn[aria-pressed="true"] + .subject-quick-btn { border-left-color: transparent; }
.subject-quick-btn > .subj-dot { display: none; }

/* Drawer destinations — spec: 56dp pill items, secondary-container active,
   label-large, active weight 700. */
.nav-section-label {
  padding: var(--md-sys-measurement-space200) var(--md-sys-measurement-space150)
    var(--md-sys-measurement-space50);
  font-size: var(--md-sys-typescale-title-small-size);
  line-height: var(--md-sys-typescale-title-small-line);
  font-weight: var(--md-sys-typescale-title-small-weight);
  letter-spacing: var(--md-sys-typescale-title-small-tracking);
  color: var(--md-sys-color-on-surface-variant);
}
.main-nav { display: flex; flex-direction: column; gap: var(--md-sys-measurement-space25); }
.main-nav button {
  position: relative;
  display: flex;
  align-items: center;
  gap: var(--md-sys-measurement-space150);
  width: 100%;
  min-height: var(--md-comp-nav-drawer-item-height);
  padding: 0 var(--md-sys-measurement-space200);
  border: 0;
  border-radius: var(--md-sys-shape-corner-full);
  background: transparent;
  color: var(--md-sys-color-on-surface-variant);
  font-size: var(--md-sys-typescale-label-large-size);
  line-height: var(--md-sys-typescale-label-large-line);
  font-weight: var(--md-sys-typescale-label-large-weight);
  text-align: left;
  transition: background-color var(--md-sys-motion-duration-short3)
    var(--md-sys-motion-easing-standard),
    color var(--md-sys-motion-duration-short3) var(--md-sys-motion-easing-standard);
}
.main-nav button:hover {
  background: color-mix(in srgb, var(--md-sys-color-on-surface) 8%, transparent);
  color: var(--md-sys-color-on-surface);
}
.main-nav button.active,
.main-nav button[aria-current="page"] {
  background: var(--md-sys-color-secondary-container);
  color: var(--md-sys-color-on-secondary-container);
  font-weight: var(--md-sys-typescale-weight-bold);
}
.nav-icon { display: inline-grid; place-items: center; width: 24px; height: 24px; flex-shrink: 0; }
.nav-label { flex: 1 1 auto; min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.nav-badge {
  flex-shrink: 0;
  min-width: 20px;
  padding: 0 var(--md-sys-measurement-space75);
  min-height: 20px;
  display: inline-grid;
  place-items: center;
  border-radius: var(--md-sys-shape-corner-full);
  background: var(--md-sys-color-surface-container-high);
  color: var(--md-sys-color-on-surface-variant);
  font-size: var(--md-sys-typescale-label-small-size);
  font-weight: var(--md-sys-typescale-label-small-weight);
  font-variant-numeric: tabular-nums;
}
.main-nav button.active .nav-badge {
  background: var(--md-sys-color-surface);
  color: var(--md-sys-color-on-surface);
}
.nav-expand-chevron {
  display: inline-grid;
  place-items: center;
  width: 20px;
  height: 20px;
  flex-shrink: 0;
  transition: transform var(--md-sys-motion-duration-short4)
    var(--md-sys-motion-easing-standard);
}
.main-nav button.expanded .nav-expand-chevron { transform: rotate(180deg); }

.nav-chapter-list {
  display: flex;
  flex-direction: column;
  gap: 2px;
  margin: var(--md-sys-measurement-space25) 0 var(--md-sys-measurement-space75)
    var(--md-sys-measurement-space300);
  padding: 0 0 0 var(--md-sys-measurement-space150);
  border-left: 1px solid var(--md-sys-color-outline-variant);
  max-height: 40vh;
  overflow-y: auto;
  overscroll-behavior: contain;
}
.nav-chapter-item {
  display: flex;
  align-items: center;
  gap: var(--md-sys-measurement-space100);
  width: 100%;
  min-height: var(--md-comp-target-size);
  padding: var(--md-sys-measurement-space75) var(--md-sys-measurement-space125);
  border: 0;
  border-radius: var(--md-sys-shape-corner-small);
  background: transparent;
  color: var(--md-sys-color-on-surface-variant);
  font-size: var(--md-sys-typescale-body-medium-size);
  line-height: 1.4;
  text-align: left;
  transition: background-color var(--md-sys-motion-duration-short2)
    var(--md-sys-motion-easing-standard);
}
.nav-chapter-item:hover {
  background: color-mix(in srgb, var(--md-sys-color-on-surface) 8%, transparent);
  color: var(--md-sys-color-on-surface);
}
.nav-chapter-item.active {
  background: var(--md-sys-color-secondary-container);
  color: var(--md-sys-color-on-secondary-container);
  font-weight: var(--md-sys-typescale-weight-medium);
}
.nav-ch-text { flex: 1 1 auto; min-width: 0; }
.nav-ch-read {
  color: var(--md-sys-color-tertiary);
  font-size: var(--md-sys-typescale-label-small-size);
  flex-shrink: 0;
}

.sidebar-bottom {
  flex-shrink: 0;
  display: flex;
  flex-direction: column;
  gap: var(--md-sys-measurement-space100);
  padding: var(--md-sys-measurement-space150) var(--md-sys-measurement-space200)
    calc(var(--md-sys-measurement-space200) + var(--layout-safe-bottom));
  border-top: 1px solid var(--md-sys-color-outline);
}
.mini-progress {
  font-size: var(--md-sys-typescale-body-small-size);
  color: var(--md-sys-color-on-surface-variant);
  line-height: 1.5;
}
.mini-progress b { color: var(--md-sys-color-on-surface); font-weight: var(--md-sys-typescale-weight-medium); }
.mini-progress .bar { margin-top: var(--md-sys-measurement-space75); }
.sidebar-links { display: flex; flex-direction: column; gap: 0; }
.text-button {
  display: inline-flex;
  align-items: center;
  gap: var(--md-sys-measurement-space100);
  min-height: var(--md-comp-target-size);
  padding: 0 var(--md-sys-measurement-space150);
  margin: 0;
  border: 0;
  border-radius: var(--md-sys-shape-corner-full);
  background: transparent;
  color: var(--md-sys-color-on-surface-variant);
  font-size: var(--md-sys-typescale-label-large-size);
  font-weight: var(--md-sys-typescale-label-large-weight);
  text-align: left;
  transition: background-color var(--md-sys-motion-duration-short2)
      var(--md-sys-motion-easing-standard),
    color var(--md-sys-motion-duration-short2) var(--md-sys-motion-easing-standard);
}
.text-button:hover {
  background: color-mix(in srgb, var(--md-sys-color-on-surface) 8%, transparent);
  color: var(--md-sys-color-on-surface);
}
.text-button svg {
  flex-shrink: 0;
  width: var(--md-comp-button-icon-size);
  height: var(--md-comp-button-icon-size);
}

/* Expanded/large/extra-large windows: standard navigation drawer (spec: 840dp+).
   The app-bar menu icon collapses it (M3 dismissible pattern). */
@media (min-width: 840px) {
  .main-column { padding-left: var(--md-comp-nav-drawer-container-width); }
  .sidebar {
    transform: none;
    background: var(--md-sys-color-surface);
    border-radius: 0;
    box-shadow: none;
    z-index: var(--z-drawer);
  }
  body.menu-open .sidebar { box-shadow: none; border-radius: 0; }
  body.drawer-collapsed .main-column { padding-left: 0; }
  body.drawer-collapsed .sidebar {
    transform: translateX(-100%);
    box-shadow: var(--md-sys-elevation-level1);
  }
  body.drawer-collapsed .scrim { opacity: 0; visibility: hidden; pointer-events: none; }
  .sidebar .drawer-close { display: none; }
}

/* ---------------------------------------------------------------------------
   Navigation rail — medium windows 600–839dp (spec: 80dp rail, 56×32 indicator)
   --------------------------------------------------------------------------- */
.nav-rail {
  position: fixed;
  inset: 0 auto 0 0;
  z-index: calc(var(--z-drawer) - 1);
  display: none;
  width: var(--md-comp-nav-rail-container-width);
  flex-direction: column;
  align-items: center;
  gap: var(--md-sys-measurement-space150);
  padding: var(--md-sys-measurement-space200) 0;
  background: var(--md-sys-color-surface);
  border-right: 0;
}
.nav-rail-brand {
  position: relative;
  display: inline-grid;
  place-items: center;
  width: var(--md-comp-target-size);
  height: var(--md-comp-target-size);
  margin-bottom: var(--md-sys-measurement-space150);
  border-radius: var(--md-sys-shape-corner-medium);
  background: var(--md-sys-color-primary-container);
  color: var(--md-sys-color-on-primary-container);
  border: 0;
}
.nav-rail-brand::before {
  content: "";
  position: absolute;
  inset: -4px;
  min-width: var(--md-comp-target-size);
  min-height: var(--md-comp-target-size);
  border-radius: inherit;
}
.nav-rail-list {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--md-sys-measurement-space150);
  width: 100%;
  padding: 0 var(--md-sys-measurement-space150);
}
.nav-rail-item {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--md-sys-measurement-space50);
  width: 100%;
  min-height: 56px;
  padding: var(--md-sys-measurement-space50) 0;
  border: 0;
  border-radius: var(--md-sys-shape-corner-full);
  background: transparent;
  color: var(--md-sys-color-on-surface-variant);
  font-size: var(--md-sys-typescale-label-medium-size);
  font-weight: var(--md-sys-typescale-label-medium-weight);
  text-align: center;
}
.nav-rail-icon {
  display: grid;
  place-items: center;
  width: var(--md-comp-nav-rail-active-indicator-width);
  height: var(--md-comp-nav-rail-active-indicator-height);
  border-radius: var(--md-sys-shape-corner-full);
  transition: background-color var(--md-sys-motion-duration-short3)
    var(--md-sys-motion-easing-standard);
}
.nav-rail-icon svg { width: var(--md-comp-nav-rail-icon-size, 24px); height: var(--md-comp-nav-rail-icon-size, 24px); }
.nav-rail-item:hover .nav-rail-icon {
  background: color-mix(in srgb, var(--md-sys-color-on-surface) 8%, transparent);
}
.nav-rail-item.active,
.nav-rail-item[aria-current="page"] { color: var(--md-sys-color-on-surface); }
.nav-rail-item.active .nav-rail-icon,
.nav-rail-item[aria-current="page"] .nav-rail-icon {
  background: var(--md-sys-color-secondary-container);
  color: var(--md-sys-color-on-secondary-container);
}
body.menu-open .nav-rail { visibility: hidden; }
.nav-rail-item.active .nav-rail-label,
.nav-rail-item[aria-current="page"] .nav-rail-label {
  font-weight: var(--md-sys-typescale-weight-bold);
}
@media (min-width: 600px) and (max-width: 839px) {
  .nav-rail { display: flex; }
  .main-column { padding-left: var(--md-comp-nav-rail-container-width); }
  #app { padding-inline: var(--layout-gutter-sm); }
  .topbar { padding-inline: var(--md-sys-measurement-space200); }
}

/* ---------------------------------------------------------------------------
   Top app bar — small app bar 64dp, surface; on scroll surface-container + lvl2.
   --------------------------------------------------------------------------- */
.topbar {
  position: sticky;
  top: 0;
  z-index: var(--z-topbar);
  display: flex;
  align-items: center;
  gap: var(--md-sys-measurement-space100);
  height: calc(var(--layout-topbar-height) + var(--layout-safe-top));
  min-height: calc(var(--layout-topbar-height) + var(--layout-safe-top));
  max-height: calc(var(--layout-topbar-height) + var(--layout-safe-top));
  box-sizing: border-box;
  overflow: visible;
  padding: var(--layout-safe-top) var(--layout-gutter-sm) 0 var(--layout-gutter);
  background: var(--md-sys-color-surface);
  border-bottom: 0;
  transition: background-color var(--md-sys-motion-duration-short3)
      var(--md-sys-motion-easing-standard),
    box-shadow var(--md-sys-motion-duration-short3)
      var(--md-sys-motion-easing-standard);
}
.topbar.is-scrolled {
  background: var(--md-sys-color-surface-container);
  box-shadow: var(--md-sys-elevation-level2);
}
.nav-menu-btn { flex-shrink: 0; }
/* Navigation menu icon (M3 menu icon button): opens the modal drawer below
   840dp and collapses/expands the standard drawer on expanded windows.
   Icon buttons keep the 40dp visual container but expose a 48dp target;
   the state layer stays 40dp thanks to background-clip. */
.topbar .icon-button {
  flex-shrink: 0;
  width: var(--md-comp-icon-button-target-size);
  height: var(--md-comp-icon-button-target-size);
  padding: calc((var(--md-comp-icon-button-target-size) -
        var(--md-comp-icon-button-container-height)) / 2);
  background-clip: content-box;
}
.topbar .nav-menu-btn { display: inline-grid; }
.breadcrumb {
  display: flex;
  align-items: center;
  gap: 2px;
  min-width: 0;
  flex: 1 1 auto;
  overflow: hidden;
  white-space: nowrap;
  font-size: var(--md-sys-typescale-label-large-size);
  color: var(--md-sys-color-on-surface-variant);
}
.crumb-btn {
  border: 0;
  background: transparent;
  min-height: var(--md-comp-target-size);
  padding: 0 var(--md-sys-measurement-space100);
  border-radius: var(--md-sys-shape-corner-full);
  color: var(--md-sys-color-on-surface-variant);
  font-size: var(--md-sys-typescale-label-large-size);
  font-weight: var(--md-sys-typescale-label-large-weight);
  white-space: nowrap;
  flex-shrink: 0;
  max-width: 40vw;
  overflow: hidden;
  text-overflow: ellipsis;
  transition: background-color var(--md-sys-motion-duration-short2)
    var(--md-sys-motion-easing-standard);
}
.crumb-btn:hover { background: color-mix(in srgb, var(--md-sys-color-on-surface) 8%, transparent); color: var(--md-sys-color-on-surface); }
/* Current location is the app-bar title: spec app-bar title = title-large. */
.crumb-current {
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  padding: 0 var(--md-sys-measurement-space50);
  color: var(--md-sys-color-on-surface);
  font-size: var(--md-sys-typescale-title-large-size);
  line-height: var(--md-sys-typescale-title-large-line);
  font-weight: var(--md-sys-typescale-title-large-weight);
  letter-spacing: var(--md-sys-typescale-title-large-tracking);
}
.crumb-sep {
  flex-shrink: 0;
  color: var(--md-sys-color-on-surface-variant);
  font-size: var(--md-sys-typescale-label-large-size);
  user-select: none;
}
.top-actions { display: flex; align-items: center; gap: var(--md-sys-measurement-space25); flex-shrink: 0; }

/* Search bar trigger — spec search bar: 56dp, full round, surface-container-high. */
.search-trigger {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: var(--md-sys-measurement-space100);
  height: var(--md-comp-search-bar-container-height);
  min-width: 0;
  padding: 0 var(--md-sys-measurement-space200);
  margin-right: var(--md-sys-measurement-space50);
  border: 0;
  border-radius: var(--md-comp-search-bar-container-shape);
  background: var(--md-comp-search-bar-container-color);
  color: var(--md-sys-color-on-surface-variant);
  text-align: left;
  transition: background-color var(--md-sys-motion-duration-short3)
      var(--md-sys-motion-easing-standard),
    box-shadow var(--md-sys-motion-duration-short3)
      var(--md-sys-motion-easing-standard);
}
.search-trigger::before {
  content: "";
  position: absolute;
  inset: -4px;
  min-width: var(--md-comp-target-size);
  min-height: var(--md-comp-target-size);
  border-radius: inherit;
}
.search-trigger:hover {
  background: var(--md-sys-color-surface-container-highest);
  box-shadow: var(--md-sys-elevation-level1);
}
.search-trigger svg { flex-shrink: 0; width: 24px; height: 24px; }
.search-trigger-text {
  font-size: var(--md-sys-typescale-body-large-size);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  min-width: 0;
  flex: 1 1 auto;
}
.search-trigger kbd {
  flex-shrink: 0;
  padding: 2px var(--md-sys-measurement-space75);
  border: 1px solid var(--md-sys-color-outline-variant);
  border-radius: var(--md-sys-shape-corner-extra-small);
  background: transparent;
  color: var(--md-sys-color-on-surface-variant);
  font-family: var(--md-ref-typeface-plain);
  font-size: var(--md-sys-typescale-label-small-size);
  line-height: 1.4;
}
.save-status {
  font-size: var(--md-sys-typescale-label-medium-size);
  color: var(--md-sys-color-on-surface-variant);
  white-space: nowrap;
  padding: 0 var(--md-sys-measurement-space50);
  min-width: 0;
}
.save-status:empty { display: none; }

.reading-progress-bar {
  position: fixed;
  top: calc(var(--layout-topbar-height) + var(--layout-safe-top));
  left: 0;
  right: 0;
  z-index: calc(var(--z-topbar) + 1);
  height: var(--md-comp-progress-track-thickness);
  background: var(--md-sys-color-secondary-container);
  pointer-events: none;
}
.reading-progress-bar > span {
  display: block;
  height: 100%;
  width: 0;
  background: var(--md-sys-color-primary);
  border-radius: var(--md-sys-shape-corner-full);
  transition: width 80ms linear;
}

/* ---------------------------------------------------------------------------
   Navigation bar (bottom, compact <600dp) — 80dp, 64×32 indicators, 3–5 items.
   --------------------------------------------------------------------------- */
.bottom-nav {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: var(--z-navbar);
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  height: calc(var(--layout-nav-bar-height) + var(--layout-safe-bottom));
  padding: var(--md-sys-measurement-space150) var(--md-sys-measurement-space50)
    var(--layout-safe-bottom);
  background: var(--md-sys-color-surface-container);
  border-top: 0;
  box-shadow: var(--md-sys-elevation-level2);
  transform: translateY(0);
  transition: transform var(--md-sys-motion-duration-medium2)
    var(--md-sys-motion-easing-emphasized-decelerate);
}
.bottom-nav button {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--md-sys-measurement-space50);
  min-width: 0;
  min-height: var(--md-comp-target-size);
  padding: 0 var(--md-sys-measurement-space25);
  border: 0;
  background: transparent;
  color: var(--md-sys-color-on-surface-variant);
  border-radius: var(--md-sys-shape-corner-medium);
}
.bottom-nav-icon {
  display: inline-grid;
  place-items: center;
  width: var(--md-comp-nav-bar-active-indicator-width);
  height: var(--md-comp-nav-bar-active-indicator-height);
  border-radius: var(--md-sys-shape-corner-full);
  transition: background-color var(--md-sys-motion-duration-short3)
    var(--md-sys-motion-easing-standard);
}
.bottom-nav-icon svg { width: var(--md-comp-nav-bar-icon-size); height: var(--md-comp-nav-bar-icon-size); }
.bottom-nav-label {
  font-size: var(--md-sys-typescale-label-medium-size);
  line-height: var(--md-sys-typescale-label-medium-line);
  font-weight: var(--md-sys-typescale-label-medium-weight);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  max-width: 100%;
}
.bottom-nav button.active,
.bottom-nav button[aria-current="page"] { color: var(--md-sys-color-on-surface); }
.bottom-nav button.active .bottom-nav-icon,
.bottom-nav button[aria-current="page"] .bottom-nav-icon {
  background: var(--md-sys-color-secondary-container);
  color: var(--md-sys-color-on-secondary-container);
}
.bottom-nav button.active .bottom-nav-label,
.bottom-nav button[aria-current="page"] .bottom-nav-label {
  font-weight: var(--md-sys-typescale-weight-bold);
}

@media (max-width: 599px) {
  body.has-subject #app {
    padding-bottom: calc(var(--layout-nav-bar-height) + var(--layout-safe-bottom) +
          var(--md-sys-measurement-space300));
  }
  /* Focused/immersive flows: the in-flow action bar replaces the navigation bar. */
  body.is-immersive #app {
    padding-bottom: var(--md-sys-measurement-space600);
  }
}
/* body.is-immersive is set by app.js for quiz attempts / Rapid / flashcards. */
body.is-immersive .bottom-nav { display: none; }
@media (min-width: 600px) {
  .bottom-nav { display: none; }
}

/* ---------------------------------------------------------------------------
   Scrim
   --------------------------------------------------------------------------- */
.scrim {
  position: fixed;
  inset: 0;
  z-index: var(--z-scrim);
  /* spec navigation-drawer.scrim: ref neutral-variant20 at 40% opacity. */
  background: color-mix(in srgb, var(--md-ref-palette-neutral-variant20) 40%, transparent);
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transition: opacity var(--md-sys-motion-duration-short4)
      var(--md-sys-motion-easing-standard),
    visibility 0s linear var(--md-sys-motion-duration-short4);
}
body.menu-open .scrim {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
  transition: opacity var(--md-sys-motion-duration-short4)
    var(--md-sys-motion-easing-standard);
}
/* Modal calculator side/bottom sheet also needs its scrim (app.js closes it
   when the #overlay scrim is clicked). */
body.calc-open .scrim {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
  transition: opacity var(--md-sys-motion-duration-short4)
    var(--md-sys-motion-easing-standard);
}
body.cmd-open, body.calc-open { overflow: hidden; }

/* Modal drawer only below the permanent-drawer breakpoint. */
@media (max-width: 839px) {
  body.menu-open { overflow: hidden; }
  body.menu-open .sidebar .drawer-close { display: inline-grid; }
  body.menu-open .sidebar {
    width: min(var(--md-comp-nav-drawer-container-width),
        calc(100vw - var(--md-sys-measurement-space400)));
  }
}

.cmd-search-bar .icon-button,
.calc-drawer .icon-button {
  width: var(--md-comp-icon-button-target-size);
  height: var(--md-comp-icon-button-target-size);
  padding: calc((var(--md-comp-icon-button-target-size) -
        var(--md-comp-icon-button-container-height)) / 2);
  background-clip: content-box;
}

/* ---------------------------------------------------------------------------
   Search view (#cmdModal) — docked search on ≥600, full-screen below.
   --------------------------------------------------------------------------- */
.cmd-backdrop {
  position: fixed;
  inset: 0;
  z-index: var(--z-modal);
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: max(var(--md-sys-measurement-space150), var(--layout-safe-top))
    var(--md-sys-measurement-space150) var(--md-sys-measurement-space150);
  background: color-mix(in srgb, var(--md-sys-color-scrim) 32%, transparent);
  overflow-y: auto;
  overscroll-behavior: contain;
}
.cmd-dialog {
  display: flex;
  flex-direction: column;
  width: min(720px, 100%);
  max-height: min(76vh, 760px);
  margin-top: 5vh;
  background: var(--md-sys-color-surface-container-high);
  border-radius: var(--md-sys-shape-corner-extra-large);
  box-shadow: var(--md-sys-elevation-level3);
  overflow: hidden;
  animation: m3-dialog-in var(--md-sys-motion-duration-medium2)
    var(--md-sys-motion-easing-emphasized-decelerate) both;
}
@keyframes m3-dialog-in {
  from { opacity: 0; transform: translateY(-8px); }
  to { opacity: 1; transform: none; }
}
.cmd-search-bar {
  display: flex;
  align-items: center;
  gap: var(--md-sys-measurement-space100);
  /* spec search bar: 56dp (docked search-view header height is 56dp too). */
  height: var(--md-comp-search-bar-container-height);
  padding: 0 var(--md-sys-measurement-space100) 0 var(--md-sys-measurement-space200);
  flex-shrink: 0;
  color: var(--md-sys-color-on-surface-variant);
}
.cmd-search-bar svg { flex-shrink: 0; width: var(--md-comp-search-bar-icon-size); height: var(--md-comp-search-bar-icon-size); }
.cmd-search-bar kbd {
  font-family: var(--md-ref-typeface-plain);
  font-size: var(--md-sys-typescale-label-small-size);
  line-height: var(--md-sys-typescale-label-small-line);
  color: var(--md-sys-color-on-surface-variant);
}
.cmd-search-bar input {
  flex: 1 1 auto;
  min-width: 0;
  height: 48px;
  padding: 0 var(--md-sys-measurement-space100);
  border: 0;
  background: transparent;
  color: var(--md-sys-color-on-surface);
  font-size: var(--md-sys-typescale-body-large-size);
  outline: none;
  box-shadow: none;
}
.cmd-search-bar input::placeholder { color: var(--md-sys-color-on-surface-variant); }
.cmd-search-bar input:hover,
.cmd-search-bar input:focus { border: 0; box-shadow: none; }
.cmd-results {
  flex: 1 1 auto;
  min-height: 0;
  overflow-y: auto;
  overscroll-behavior: contain;
  padding: var(--md-sys-measurement-space50) var(--md-sys-measurement-space100)
    var(--md-sys-measurement-space150);
  border-top: 1px solid var(--md-sys-color-outline);
}
.cmd-item {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: var(--md-sys-measurement-space150);
  width: 100%;
  min-height: 56px;
  padding: var(--md-sys-measurement-space150) var(--md-sys-measurement-space150);
  border: 0;
  border-radius: var(--md-sys-shape-corner-medium);
  background: transparent;
  text-align: left;
  color: var(--md-sys-color-on-surface);
  transition: background-color var(--md-sys-motion-duration-short2)
    var(--md-sys-motion-easing-standard);
}
.cmd-item:hover,
.cmd-item:focus-visible,
.cmd-item.is-active { background: var(--md-sys-color-surface-container-highest); }
.cmd-item > div { min-width: 0; display: flex; flex-direction: column; gap: var(--md-sys-measurement-space25); }
.cmd-item b {
  font-size: var(--md-sys-typescale-body-large-size);
  font-weight: var(--md-sys-typescale-weight-medium);
  line-height: 1.4;
}
.cmd-item small { font-size: var(--md-sys-typescale-body-small-size); color: var(--md-sys-color-on-surface-variant); }
.cmd-snippet {
  font-size: var(--md-sys-typescale-body-medium-size);
  color: var(--md-sys-color-on-surface-variant);
  line-height: 1.5;
  overflow: hidden;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
}
.cmd-tag {
  flex-shrink: 0;
  padding: 0 var(--md-sys-measurement-space100);
  min-height: 24px;
  display: inline-grid;
  place-items: center;
  border-radius: var(--md-sys-shape-corner-small);
  background: var(--md-sys-color-secondary-container);
  color: var(--md-sys-color-on-secondary-container);
  font-size: var(--md-sys-typescale-label-small-size);
  font-weight: var(--md-sys-typescale-label-small-weight);
  white-space: nowrap;
}
.cmd-results mark,
mark {
  background: var(--md-sys-color-primary-container);
  color: var(--md-sys-color-on-primary-container);
  border-radius: var(--md-sys-shape-corner-extra-small);
  padding: 0 var(--md-sys-measurement-space25);
}
.cmd-results .empty {
  padding: var(--md-sys-measurement-space400) var(--md-sys-measurement-space250);
  text-align: center;
  color: var(--md-sys-color-on-surface-variant);
}

@media (max-width: 599px) {
  .cmd-backdrop { padding: 0; align-items: stretch; background: var(--md-sys-color-surface); }
  .cmd-dialog {
    width: 100%;
    max-height: none;
    height: 100dvh;
    margin-top: 0;
    border-radius: 0;
    box-shadow: none;
    animation: none;
  }
  .cmd-search-bar {
    height: calc(var(--md-sys-measurement-space900) + var(--layout-safe-top));
    padding: var(--layout-safe-top) var(--md-sys-measurement-space100) 0
      var(--md-sys-measurement-space200);
    border-bottom: 1px solid var(--md-sys-color-outline);
  }
  .cmd-results { padding: var(--md-sys-measurement-space100) var(--md-sys-measurement-space100)
      calc(var(--md-sys-measurement-space250) + var(--layout-safe-bottom)); }
}

/* ---------------------------------------------------------------------------
   Calculator side sheet (docked 256dp on desktop) / bottom sheet on compact.
   --------------------------------------------------------------------------- */
.calc-drawer {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  z-index: var(--z-modal);
  display: flex;
  flex-direction: column;
  /* Modal side sheet: surface-container-low, large start shape, level 1.
     Spec docked width is 256dp; 256dp cannot hold this 5-column keypad with
     48dp keys, so the 360dp drawer token is used as sheet width (documented
     exception in reports/shell.md). */
  width: min(var(--md-comp-nav-drawer-container-width), 92vw);
  background: var(--md-sys-color-surface-container-low);
  border-left: 0;
  border-radius: var(--md-sys-shape-corner-large-start);
  box-shadow: var(--md-sys-elevation-level1);
  transform: translateX(101%);
  transition: transform var(--md-sys-motion-duration-medium2)
    var(--md-sys-motion-easing-emphasized-decelerate);
}
.calc-drawer.is-open { transform: translateX(0); }
.calc-drawer-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: var(--md-sys-measurement-space150);
  padding: var(--md-sys-measurement-space200) var(--md-sys-measurement-space150)
    var(--md-sys-measurement-space150) var(--md-sys-measurement-space250);
  border-bottom: 1px solid var(--md-sys-color-outline);
  flex-shrink: 0;
}
.calc-drawer-head > div { min-width: 0; }
.calc-drawer-head strong {
  display: block;
  font-size: var(--md-sys-typescale-title-large-size);
  font-weight: var(--md-sys-typescale-title-large-weight);
}
.calc-drawer-head small {
  display: block;
  margin-top: var(--md-sys-measurement-space25);
  font-size: var(--md-sys-typescale-body-small-size);
  color: var(--md-sys-color-on-surface-variant);
  line-height: 1.45;
}
.calc-drawer-body {
  flex: 1 1 auto;
  min-height: 0;
  overflow-y: auto;
  overscroll-behavior: contain;
  padding: var(--md-sys-measurement-space200) var(--md-sys-measurement-space250)
    calc(var(--md-sys-measurement-space250) + var(--layout-safe-bottom));
  display: flex;
  flex-direction: column;
  gap: var(--md-sys-measurement-space150);
}
.calc-expr-row { display: flex; }
.calc-expr-input,
.scratch-area {
  width: 100%;
  min-height: var(--md-comp-text-field-container-height);
  padding: 0 var(--md-sys-measurement-space200);
  border: var(--md-comp-text-field-outline-width) solid var(--md-sys-color-outline);
  border-radius: var(--md-comp-text-field-container-shape);
  background: transparent;
  color: var(--md-sys-color-on-surface);
  font-size: var(--md-sys-typescale-body-large-size);
  font-variant-numeric: tabular-nums;
  outline: none;
  transition: border-color var(--md-sys-motion-duration-short2)
    var(--md-sys-motion-easing-standard);
}
.scratch-area {
  min-height: 112px;
  padding: var(--md-sys-measurement-space150) var(--md-sys-measurement-space200);
  font-size: var(--md-sys-typescale-body-medium-size);
  line-height: 1.6;
  resize: vertical;
}
.calc-expr-input:focus, .scratch-area:focus { border-color: var(--md-sys-color-primary); }
.calc-result-bar {
  padding: var(--md-sys-measurement-space150) var(--md-sys-measurement-space200);
  border-radius: var(--md-sys-shape-corner-medium);
  background: var(--md-sys-color-surface-container);
  color: var(--md-sys-color-on-surface-variant);
  font-size: var(--md-sys-typescale-body-medium-size);
}
.calc-result-bar[data-error="true"] {
  background: var(--md-sys-color-error-container);
  color: var(--md-sys-color-on-error-container);
}
.calc-result-bar b {
  color: var(--md-sys-color-on-surface);
  font-size: var(--md-sys-typescale-title-medium-size);
  font-variant-numeric: tabular-nums;
}
.calc-hint { color: var(--md-sys-color-on-surface-variant); }
.calc-keypad {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: var(--md-sys-measurement-space75);
}
.calc-key {
  min-height: 48px;
  padding: 0;
  border: 0;
  border-radius: var(--md-sys-shape-corner-medium);
  background: var(--md-sys-color-surface-container-high);
  color: var(--md-sys-color-on-surface);
  font-size: var(--md-sys-typescale-title-medium-size);
  font-weight: var(--md-sys-typescale-title-medium-weight);
  transition: background-color var(--md-sys-motion-duration-short1)
    var(--md-sys-motion-easing-standard);
}
.calc-key:hover { background: var(--md-sys-color-surface-container-highest); }
.calc-key.key-op {
  background: var(--md-sys-color-secondary-container);
  color: var(--md-sys-color-on-secondary-container);
}
.calc-key.key-eq { background: var(--md-sys-color-primary); color: var(--md-sys-color-on-primary); }
.calc-key.key-clear, .calc-key.key-fn {
  background: var(--md-sys-color-surface-container);
  color: var(--md-sys-color-on-surface-variant);
}
.calc-history { display: flex; flex-direction: column; gap: 2px; max-height: 120px; overflow-y: auto; }
.calc-hist-item {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--md-sys-measurement-space150);
  padding: var(--md-sys-measurement-space75) var(--md-sys-measurement-space125);
  border: 0;
  border-radius: var(--md-sys-shape-corner-small);
  background: transparent;
  font-size: var(--md-sys-typescale-body-medium-size);
  color: var(--md-sys-color-on-surface-variant);
  cursor: pointer;
  min-height: var(--md-comp-target-size);
  text-align: left;
}
.calc-hist-item:hover, .calc-hist-item:focus-visible {
  background: var(--md-sys-color-surface-container-high);
  color: var(--md-sys-color-on-surface);
}
.calc-hist-item b {
  font-weight: var(--md-sys-typescale-weight-medium);
  color: var(--md-sys-color-primary);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}
.calc-hist-item span { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.scratch-label {
  margin-top: var(--md-sys-measurement-space50);
  font-size: var(--md-sys-typescale-label-medium-size);
  color: var(--md-sys-color-on-surface-variant);
  line-height: 1.45;
}

/* Compact windows: calculator becomes a modal bottom sheet (spec sheet.bottom:
   surface-container-low, extra-large top corners, 32×4 drag handle, level 1). */
@media (max-width: 599px) {
  .calc-drawer {
    top: auto;
    left: 0;
    right: 0;
    bottom: 0;
    width: 100%;
    /* 92vw + the legacy max-width: calc(100vw - 28px) left a 28px gap on the
       right, which read as an off-centre sheet. A compact bottom sheet is
       full-bleed here. */
    max-width: none;
    margin: 0;
    max-height: calc(100dvh - var(--md-sys-measurement-space900));
    border-radius: var(--md-comp-sheet-container-shape);
    box-shadow: var(--md-sys-elevation-level1);
    transform: translateY(101%);
  }
  .calc-drawer::before {
    content: "";
    align-self: center;
    width: var(--md-comp-sheet-drag-handle-width);
    height: var(--md-comp-sheet-drag-handle-height);
    margin-top: var(--md-sys-measurement-space100);
    border-radius: var(--md-sys-shape-corner-full);
    background: var(--md-sys-color-on-surface-variant);
    opacity: var(--md-comp-sheet-drag-handle-opacity);
    flex-shrink: 0;
  }
  .calc-drawer.is-open { transform: translateY(0); }
  .calc-drawer-head {
    padding-top: var(--md-sys-measurement-space100);
    border-bottom: 0;
  }
  .calc-keypad { gap: var(--md-sys-measurement-space100); }
  .calc-key { min-height: 52px; }
}

/* ---------------------------------------------------------------------------
   Snackbar (toast) — inverse-surface, 4dp corner, elevation 3.
   --------------------------------------------------------------------------- */
.toast {
  position: fixed;
  left: 50%;
  bottom: calc(var(--md-sys-measurement-space300) + var(--layout-safe-bottom));
  z-index: var(--z-toast);
  display: none;
  max-width: min(560px, calc(100vw - 32px));
  min-height: var(--md-comp-snackbar-one-line-height);
  align-items: center;
  padding: var(--md-sys-measurement-space175) var(--md-sys-measurement-space200);
  border-radius: var(--md-comp-snackbar-container-shape);
  background: var(--md-comp-snackbar-container-color);
  color: var(--md-sys-color-inverse-on-surface);
  font-size: var(--md-sys-typescale-body-medium-size);
  line-height: var(--md-sys-typescale-body-medium-line);
  box-shadow: var(--md-sys-elevation-level3);
  transform: translate(-50%, 12px);
  opacity: 0;
  transition: opacity var(--md-sys-motion-duration-short4)
      var(--md-sys-motion-easing-standard),
    transform var(--md-sys-motion-duration-short4)
      var(--md-sys-motion-easing-emphasized-decelerate);
}
.toast.show { display: flex; opacity: 1; transform: translate(-50%, 0); }
@media (max-width: 599px) {
  .toast {
    left: var(--md-sys-measurement-space200);
    right: var(--md-sys-measurement-space200);
    max-width: none;
    transform: translateY(12px);
    bottom: calc(var(--layout-nav-bar-height) + var(--layout-safe-bottom) +
          var(--md-sys-measurement-space150));
  }
  .toast.show { transform: translateY(0); }
  body.is-immersive .toast {
    bottom: calc(var(--md-sys-measurement-space300) + var(--layout-safe-bottom));
  }
}

/* ---------------------------------------------------------------------------
   Chart lightbox — modal dialog (28dp), scrim behind.
   --------------------------------------------------------------------------- */
.chart-lightbox {
  position: fixed;
  inset: 0;
  z-index: var(--z-lightbox);
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--md-sys-measurement-space200);
  background: color-mix(in srgb, var(--md-sys-color-scrim) 88%, transparent);
}
.chart-lightbox.is-open { display: flex; }
.chart-lightbox-close {
  position: absolute;
  top: calc(var(--md-sys-measurement-space150) + var(--layout-safe-top));
  right: var(--md-sys-measurement-space150);
  z-index: 1;
  display: inline-grid;
  place-items: center;
  width: var(--md-comp-icon-button-target-size);
  height: var(--md-comp-icon-button-target-size);
  padding: calc((var(--md-comp-icon-button-target-size) -
        var(--md-comp-icon-button-container-height)) / 2);
  border: 0;
  border-radius: var(--md-sys-shape-corner-full);
  background: var(--md-sys-color-surface-container-high);
  background-clip: content-box;
  color: var(--md-sys-color-on-surface);
}
.chart-lightbox-close:hover {
  background: color-mix(in srgb, var(--md-sys-color-on-surface) 8%, transparent);
  background-clip: content-box;
}
.chart-lightbox-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--md-sys-measurement-space150);
  max-width: 96vw;
  max-height: 92vh;
  padding: var(--md-sys-measurement-space100);
  border-radius: var(--md-comp-dialog-container-shape);
  background: var(--md-sys-color-surface-container-high);
  box-shadow: var(--md-sys-elevation-level3);
}
.chart-lightbox-img-wrap {
  display: flex;
  align-items: center;
  justify-content: center;
  max-width: 94vw;
  max-height: 78vh;
  border-radius: var(--md-sys-shape-corner-large);
  overflow: auto;
  background: var(--md-sys-color-surface);
}
.chart-lightbox-img { display: block; max-width: 94vw; max-height: 78vh; object-fit: contain; }
.chart-lightbox-caption {
  max-width: 820px;
  color: var(--md-sys-color-on-surface-variant);
  font-size: var(--md-sys-typescale-body-medium-size);
  text-align: center;
  line-height: 1.5;
  padding: 0 var(--md-sys-measurement-space150) var(--md-sys-measurement-space100);
}
.chart-lightbox-caption b {
  display: block;
  color: var(--md-sys-color-on-surface);
  font-weight: var(--md-sys-typescale-weight-medium);
}

/* ---------------------------------------------------------------------------
   Compact (window size class) refinements
   --------------------------------------------------------------------------- */
@media (max-width: 599px) {
  #app {
    padding: var(--md-sys-measurement-space200) var(--layout-gutter)
      var(--md-sys-measurement-space400);
  }
  .topbar {
    padding: var(--layout-safe-top) var(--md-sys-measurement-space50) 0
      var(--md-sys-measurement-space50);
    gap: var(--md-sys-measurement-space50);
    height: calc(var(--layout-topbar-height) + var(--layout-safe-top));
    min-height: calc(var(--layout-topbar-height) + var(--layout-safe-top));
    max-height: calc(var(--layout-topbar-height) + var(--layout-safe-top));
  }
  .breadcrumb .crumb-btn,
  .breadcrumb .crumb-sep { display: none; }
  /* Compact title: title-medium keeps the location readable with 4 bar items
     at 320–390dp (spec small app bar role is title-large; documented). */
  .crumb-current {
    font-size: var(--md-sys-typescale-title-medium-size);
    line-height: var(--md-sys-typescale-title-medium-line);
    font-weight: var(--md-sys-typescale-title-medium-weight);
    padding-inline: var(--md-sys-measurement-space50);
  }
  .search-trigger {
    width: var(--md-comp-icon-button-target-size);
    height: var(--md-comp-icon-button-target-size);
    min-width: var(--md-comp-icon-button-target-size);
    padding: calc((var(--md-comp-icon-button-target-size) -
          var(--md-comp-icon-button-container-height)) / 2);
    justify-content: center;
    margin-right: 0;
    background-clip: content-box;
  }
  .search-trigger-text, .search-trigger kbd { display: none; }
  .save-status { display: none; }
  .page-head { margin-bottom: var(--md-sys-measurement-space200); }
  .section-title { margin: var(--md-sys-measurement-space300) 0 var(--md-sys-measurement-space150); }
}
@media (max-width: 359px) {
  #app { padding-inline: var(--md-sys-measurement-space150); }
  /* 320dp: keep one primary search action; the rest stays in the drawer. */
  .top-actions [data-action="toggle-theme"] { display: none; }
}

/* ---------- reduced motion ---------- */
@media (prefers-reduced-motion: reduce) {
  .sidebar, .calc-drawer, .toast, .scrim, .cmd-dialog { transition: none; animation: none; }
  #app.view-enter > * { animation: none; }
}