/* Study materials — extends quiz-browser.css (/quiz same shell)
   Hierarchy: Subject (accent stripe) → Topic (rail + header) → Chapter (pill + dashed rail) → PDF row */

.sm-study-page {
  --sm-rail-topic: rgba(17, 85, 204, .22);
  --sm-rail-chapter: rgba(100, 116, 139, .4);
  --sm-topic-bg: rgba(17, 85, 204, .055);
  --sm-subject-bg: #f1f5f9;
}

/* ── Desktop: breathe from left edge ───────────────────── */
@media (min-width: 901px) {
  .quiz-app-page.sm-study-page .quiz-layout {
    padding-left: 24px;
    box-sizing: border-box;
  }

  .quiz-app-page.sm-study-page .quiz-sidebar {
    border-radius: 0 14px 0 0;
    border-right: 1px solid rgba(226, 232, 240, .95);
    box-shadow: 4px 0 24px rgba(15, 23, 42, .04);
  }

  .quiz-app-page.sm-study-page nav.quiz-sidebar-nav {
    padding: 10px 12px 28px 16px;
  }

  .quiz-app-page.sm-study-page .quiz-main.sm-study-main {
    padding-left: 44px;
    padding-right: 40px;
    padding-top: 32px;
  }
}

/* ── Subject (top level) ───────────────────────────────── */
.sm-study-page .sm-study-subject-block {
  margin-bottom: 14px;
}

.sm-study-page .sm-study-subject-block:last-of-type {
  margin-bottom: 4px;
}

.sm-study-page .sm-study-subject-block > .subject-btn {
  position: relative;
  margin: 0 2px 0 0;
  padding: 12px 14px 12px 14px;
  border-radius: 12px;
  border: 1px solid rgba(226, 232, 240, .95);
  border-left: 4px solid var(--sm-accent, var(--blue));
  background: linear-gradient(
    105deg,
    color-mix(in srgb, var(--sm-accent, var(--blue)) 11%, var(--sm-subject-bg)) 0%,
    var(--sm-subject-bg) 56%,
    #fff 100%
  );
  box-shadow: 0 1px 2px rgba(15, 23, 42, .05);
  font-size: 15px;
  font-weight: 800;
  letter-spacing: -0.01em;
  line-height: 1.25;
}

.sm-study-page .sm-study-subject-block > .subject-btn:hover,
.sm-study-page .sm-study-subject-block > .subject-btn.active {
  background: linear-gradient(
    105deg,
    color-mix(in srgb, var(--sm-accent, var(--blue)) 16%, var(--blue-lt)) 0%,
    var(--blue-lt) 50%,
    #fff 100%
  );
  color: var(--blue);
}

.sm-study-page .sm-study-subject-block .subject-copy span {
  font-weight: 800;
}

.sm-study-page .sm-study-subject-block .subject-copy small {
  font-size: 11px;
  font-weight: 500;
  color: var(--muted);
  margin-top: 3px;
  line-height: 1.35;
}

.sm-study-page .sm-subject-meta {
  gap: 10px;
}

.sm-study-page .sm-pdf-count-badge {
  font-variant-numeric: tabular-nums;
  font-weight: 700;
  padding: 3px 9px;
  min-width: 1.75rem;
  justify-content: center;
  border: 1px solid rgba(15, 23, 42, .08);
  background: rgba(255, 255, 255, .85);
}

.sm-study-page .sm-study-subject-block > .subject-btn.active .sm-pdf-count-badge,
.sm-study-page .sm-study-subject-block > .subject-btn:hover .sm-pdf-count-badge {
  background: rgba(255, 255, 255, .95);
  border-color: rgba(17, 85, 204, .2);
  color: var(--navy);
}

/* ── Topic group (2nd level) ───────────────────────────── */
.sm-study-page .sm-study-topic-block {
  margin: 14px 0 10px 6px;
  padding: 4px 0 6px 14px;
  border-left: 3px solid var(--sm-rail-topic);
}

.sm-study-page .sm-study-topic-block:first-child {
  margin-top: 10px;
}

.sm-study-topic-head {
  display: flex;
  align-items: center;
  gap: 10px;
  width: 100%;
  padding: 11px 12px 10px 12px;
  margin: 0 0 6px;
  border-radius: 11px;
  background: var(--sm-topic-bg);
  border: 1px solid rgba(17, 85, 204, .12);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, .65);
}

.sm-study-page .sm-study-topic-head .topic-icon {
  width: 34px;
  height: 34px;
  display: grid;
  place-items: center;
  border-radius: 10px;
  background: color-mix(in srgb, var(--sm-accent, var(--blue)) 14%, #fff);
  font-size: 16px;
}

.sm-study-page .sm-study-topic-head .topic-copy {
  flex: 1;
  min-width: 0;
}

.sm-study-page .sm-study-topic-head .topic-copy > span {
  font-weight: 800;
  color: var(--navy);
  font-size: 13px;
  line-height: 1.35;
}

.sm-study-page .sm-study-topic-head .topic-copy small {
  font-size: 10px;
  font-weight: 500;
  color: var(--muted);
  margin-top: 3px;
}

.sm-study-page .sm-study-topic-head .topic-qcount {
  flex-shrink: 0;
  margin-left: 6px;
}

/* ── Chapter (3rd level) ─────────────────────────────── */
.sm-chapter-block {
  margin: 12px 0 16px;
  padding-left: 10px;
  border-left: 1px dashed var(--sm-rail-chapter);
}

.sm-chapter-inline-label {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin: 0 0 9px 2px;
  padding: 5px 12px 5px 10px;
  border-radius: 8px;
  background: linear-gradient(135deg, rgba(15, 23, 42, .07), rgba(15, 23, 42, .04));
  border: 1px solid rgba(15, 23, 42, .08);
  font: 700 10px 'DM Mono', monospace;
  text-transform: uppercase;
  letter-spacing: .1em;
  color: var(--navy);
}

.sm-chapter-inline-label::before {
  content: '';
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--gold);
  flex-shrink: 0;
  opacity: .9;
}

/* ── PDF row (4th level; compact, readable) ───────────── */
.sm-study-page .topic-btn.sm-material-btn {
  align-items: flex-start;
  margin-top: 5px;
  margin-left: 0;
  padding: 11px 12px 11px 12px;
  white-space: normal;
  border-radius: 11px;
  border: 1px solid transparent;
  border-left: 3px solid transparent;
  background: rgba(248, 250, 252, .85);
}

.sm-study-page .topic-btn.sm-material-btn:hover {
  background: var(--blue-lt);
  border-color: rgba(17, 85, 204, .12);
}

.sm-study-page .topic-btn.sm-material-btn.active {
  border-left-color: var(--sm-accent, var(--blue));
  box-shadow: 0 2px 12px rgba(17, 85, 204, .12);
}

.sm-study-page .sm-mat-ico {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border-radius: 10px;
  background: color-mix(in srgb, var(--sm-accent, var(--blue)) 12%, #fff);
  border: 1px solid rgba(17, 85, 204, .1);
  flex-shrink: 0;
}

.sm-study-page .sm-mat-ico svg {
  width: 18px;
  height: 18px;
}

.sm-study-page .sm-mat-copy span {
  font-weight: 700;
  color: var(--navy);
  font-size: 13px;
  line-height: 1.4;
}

.sm-study-page .sm-mat-copy small {
  display: block;
  margin-top: 4px;
  line-height: 1.45;
  white-space: normal;
  font-size: 11px;
  color: var(--muted);
}

.sm-study-page nav.quiz-sidebar-nav {
  flex: 1;
  min-height: 0;
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
}

.sm-reader-breadcrumb {
  margin-bottom: 12px;
  color: var(--muted);
  font: 12px 'Sora', sans-serif;
}

.sm-reader-breadcrumb span {
  color: var(--blue);
  font-weight: 600;
}

.sm-study-page .topic-list.open {
  max-height: none;
}

.sm-filter-hidden {
  display: none !important;
}

.sm-search-empty {
  font-size: 13px;
  color: var(--muted);
  text-align: center;
  padding: 20px 16px 24px;
  margin-top: 4px;
}

.quiz-app-page.sm-study-page .sm-study-panels {
  flex: 1;
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: 22px;
}

.sm-panel {
  background: var(--white);
  border-radius: 20px;
  padding: 22px 24px;
  box-shadow: var(--shadow-sm);
  border: 1px solid rgba(226, 232, 240, .9);
}

.sm-badge {
  display: inline-block;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--blue);
  background: var(--blue-lt);
  padding: 6px 12px;
  border-radius: 999px;
  margin-bottom: 12px;
}

.sm-badge-soft {
  text-transform: none;
  letter-spacing: .04em;
  font-size: 11px;
  font-weight: 600;
  line-height: 1.45;
  max-width: 100%;
  margin-bottom: 12px;
}

.sm-panel-title {
  font-size: clamp(22px, 2.6vw, 28px);
  font-weight: 800;
  color: var(--navy);
  margin-bottom: 10px;
}

.sm-panel-hint {
  font-size: 14px;
  line-height: 1.6;
  color: var(--muted);
  max-width: 720px;
}

.sm-panel-actions {
  margin-top: 16px;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.sm-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 9px 18px;
  border-radius: 999px;
  font-size: 13px;
  font-weight: 700;
  font-family: 'Sora', 'Noto Sans Devanagari', sans-serif;
  border: none;
  cursor: pointer;
  transition: transform .15s ease, filter .15s ease;
}

.sm-btn-primary {
  background: var(--blue);
  color: #fff;
  text-decoration: none;
}

.sm-btn-primary:hover {
  filter: brightness(1.05);
}

.sm-btn-outline {
  background: var(--white);
  color: var(--blue);
  border: 1px solid var(--blue-lt);
}

.sm-panel-preview {
  flex: 1;
  min-height: 420px;
  display: flex;
  flex-direction: column;
  padding: 0;
  overflow: hidden;
}

.sm-preview-empty[hidden],
.sm-preview-frame-wrap[hidden],
.sm-panel-actions[hidden],
button.sm-btn[hidden] {
  display: none !important;
}

.sm-preview-empty {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 48px 24px;
  min-height: 420px;
}

.sm-preview-icon {
  width: 88px;
  height: 88px;
  border-radius: 50%;
  background: var(--blue-lt);
  color: var(--blue);
  display: grid;
  place-items: center;
  margin-bottom: 18px;
}

.sm-preview-icon svg {
  width: 40px;
  height: 40px;
}

.sm-preview-empty-title {
  font-size: 18px;
  font-weight: 800;
  color: var(--navy);
  margin-bottom: 8px;
}

.sm-preview-empty-desc {
  font-size: 14px;
  color: var(--muted);
  line-height: 1.55;
  max-width: 380px;
}

.sm-preview-frame-wrap {
  flex: 1;
  min-height: min(72vh, 720px);
  background: #f1f5f9;
}

.sm-preview-frame {
  width: 100%;
  height: 100%;
  min-height: min(72vh, 720px);
  border: 0;
  display: block;
  background: var(--white);
}

.sm-mt {
  margin-top: 18px;
}

.sm-download-done {
  background: var(--green-lt) !important;
  color: var(--green) !important;
  border-color: transparent !important;
}

/* ── Mobile drawer: high-contrast hierarchy on blue panel ─ */
.sm-study-page .topic-btn.sm-material-btn:focus-visible {
  outline: 2px solid var(--blue);
  outline-offset: 2px;
}

@media (max-width: 900px) {
  .quiz-app-page.sm-study-page .sm-study-subject-block > .subject-btn {
    background: rgba(255, 255, 255, .12);
    border: 1px solid rgba(255, 255, 255, .18);
    border-left: 4px solid var(--gold);
    color: #fff;
    box-shadow: none;
  }

  .quiz-app-page.sm-study-page .sm-study-subject-block .subject-copy small {
    color: rgba(255, 255, 255, .78);
  }

  .quiz-app-page.sm-study-page .sm-study-subject-block > .subject-btn:hover,
  .quiz-app-page.sm-study-page .sm-study-subject-block > .subject-btn.active {
    background: rgba(255, 255, 255, .2);
    color: #fff;
  }

  .quiz-app-page.sm-study-page .sm-pdf-count-badge {
    background: rgba(255, 255, 255, .2);
    border-color: rgba(255, 255, 255, .28);
    color: #fff;
  }

  .quiz-app-page.sm-study-page .sm-study-subject-block > .subject-btn:hover .sm-pdf-count-badge,
  .quiz-app-page.sm-study-page .sm-study-subject-block > .subject-btn.active .sm-pdf-count-badge {
    background: var(--gold);
    border-color: transparent;
    color: var(--navy);
  }

  .quiz-app-page.sm-study-page .sm-study-topic-block {
    border-left-color: rgba(255, 255, 255, .35);
  }

  .quiz-app-page.sm-study-page .sm-study-topic-head {
    background: rgba(255, 255, 255, .12);
    border-color: rgba(255, 255, 255, .22);
    box-shadow: none;
  }

  .quiz-app-page.sm-study-page .sm-study-topic-head .topic-icon {
    background: rgba(255, 255, 255, .2);
  }

  .quiz-app-page.sm-study-page .sm-study-topic-head .topic-copy > span {
    color: #fff;
  }

  .quiz-app-page.sm-study-page .sm-study-topic-head .topic-copy small {
    color: rgba(255, 255, 255, .78);
  }

  .quiz-app-page.sm-study-page .sm-study-topic-head .sm-pdf-count-badge {
    background: rgba(255, 255, 255, .2);
    border-color: rgba(255, 255, 255, .28);
    color: #fff;
  }

  .quiz-app-page.sm-study-page .sm-chapter-block {
    border-left-color: rgba(255, 255, 255, .28);
  }

  .quiz-app-page.sm-study-page .sm-chapter-inline-label {
    background: rgba(255, 255, 255, .14);
    border-color: rgba(255, 255, 255, .2);
    color: rgba(255, 255, 255, .95);
  }

  .quiz-app-page.sm-study-page .sm-chapter-inline-label::before {
    background: var(--gold);
  }

  .quiz-app-page.sm-study-page .topic-btn.sm-material-btn {
    background: rgba(255, 255, 255, .1);
    color: rgba(255, 255, 255, .94);
  }

  .quiz-app-page.sm-study-page .topic-btn.sm-material-btn:hover,
  .quiz-app-page.sm-study-page .topic-btn.sm-material-btn.active {
    background: rgba(255, 255, 255, .22);
    color: #fff;
    border-color: rgba(255, 255, 255, .15);
  }

  .quiz-app-page.sm-study-page .topic-btn.sm-material-btn.active {
    border-left-color: var(--gold);
    box-shadow: none;
  }

  .quiz-app-page.sm-study-page .sm-mat-copy span {
    color: #fff;
  }

  .quiz-app-page.sm-study-page .sm-mat-copy small {
    color: rgba(255, 255, 255, .75);
  }

  .quiz-app-page.sm-study-page .sm-mat-ico {
    background: rgba(255, 255, 255, .18);
    border-color: rgba(255, 255, 255, .25);
  }

  .quiz-app-page.sm-study-page .sm-study-subject-block > .subject-btn .chevron {
    color: rgba(255, 255, 255, .82);
  }

  .quiz-app-page.sm-study-page .topic-btn.sm-material-btn:focus-visible {
    outline-color: #fff;
  }

  .quiz-app-page.sm-study-page nav.quiz-sidebar-nav {
    padding: 10px 10px 24px 12px;
  }
}

@media (max-width: 960px) {
  .quiz-app-page.sm-study-page .sm-panel-preview {
    min-height: 360px;
  }

  .quiz-app-page.sm-study-page .sm-preview-frame-wrap,
  .quiz-app-page.sm-study-page .sm-preview-frame {
    min-height: 55vh;
  }
}

@media (max-width: 600px) {
  .quiz-app-page.sm-study-page .sm-panel {
    padding: 18px 16px;
    border-radius: 16px;
  }

  .quiz-app-page.sm-study-page .sm-panel-actions .sm-btn {
    width: 100%;
    justify-content: center;
  }

  .quiz-app-page.sm-study-page .sm-preview-empty {
    padding: 32px 16px;
    min-height: 300px;
  }
}

/* Fallback when color-mix() not supported (older Safari) */
@supports not (color: color-mix(in srgb, #000 50%, #fff)) {
  .sm-study-page .sm-study-subject-block > .subject-btn {
    background: var(--sm-subject-bg);
  }

  .sm-study-page .sm-study-subject-block > .subject-btn:hover,
  .sm-study-page .sm-study-subject-block > .subject-btn.active {
    background: var(--blue-lt);
  }

  .sm-study-page .sm-study-topic-head .topic-icon {
    background: var(--blue-lt);
  }

  .sm-study-page .sm-mat-ico {
    background: var(--blue-lt);
  }
}