/* ============================================================
   CAMO AI & Organizations Research Library
   Design system matching camo.hku.hk
   ============================================================ */

/* --- Design Tokens --- */
:root {
  --crimson: #9B1B30;
  --crimson-dark: #7A1526;
  --crimson-light: rgba(155, 27, 48, 0.08);
  --crimson-glow: rgba(155, 27, 48, 0.15);
  --navy: #1B2A4A;
  --navy-deep: #111D33;
  --navy-light: #2C3E5F;

  --white: #FFFFFF;
  --off-white: #FAFBFC;
  --gray-50: #F5F6F8;
  --gray-100: #ECEEF2;
  --gray-200: #D8DCE3;
  --gray-400: #9AA0AD;
  --gray-500: #6E7585;
  --gray-600: #4A5060;
  --gray-800: #2A2F3A;

  --gold: #C4973B;
  --moss: #5A7D6E;

  --font-heading: "Frank Ruhl Libre", "Georgia", serif;
  --font-body: "Mada", "Helvetica Neue", Arial, sans-serif;

  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.08);
  --shadow-lg: 0 12px 40px rgba(0,0,0,0.12);
  --shadow-xl: 0 24px 60px rgba(0,0,0,0.16);

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;

  --transition: 0.2s ease;
  --max-width: 1400px;
}

/* --- Reset --- */
*, *::before, *::after { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  margin: 0;
  font-family: var(--font-body);
  font-size: 15px;
  line-height: 1.6;
  color: var(--gray-800);
  background: var(--off-white);
}

button, input { font: inherit; }
a { color: var(--crimson); text-decoration: none; }
a:hover { text-decoration: underline; }
img { max-width: 100%; display: block; }

/* ============================================================
   TOP BAR
   ============================================================ */
.topbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--navy-deep);
  border-bottom: 3px solid var(--crimson);
}

.topbar__inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 32px;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.topbar__brand {
  display: flex;
  align-items: center;
  gap: 16px;
}

.topbar__logo {
  font-family: var(--font-heading);
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--white);
  letter-spacing: 0.06em;
}

.topbar__sub {
  font-size: 0.72rem;
  line-height: 1.35;
  color: rgba(255,255,255,0.6);
  letter-spacing: 0.02em;
  border-left: 1px solid rgba(255,255,255,0.2);
  padding-left: 16px;
}

.topbar__links a {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 16px;
  border: 1px solid rgba(255,255,255,0.25);
  border-radius: var(--radius-sm);
  color: rgba(255,255,255,0.85);
  font-size: 0.8rem;
  letter-spacing: 0.02em;
  transition: all var(--transition);
}

.topbar__links a:hover {
  background: rgba(255,255,255,0.1);
  border-color: rgba(255,255,255,0.4);
  text-decoration: none;
}

/* ============================================================
   HERO
   ============================================================ */
.hero {
  position: relative;
  overflow: hidden;
  padding: 80px 32px 48px;
  background: var(--navy);
}

.hero__bg {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse at 15% 20%, rgba(155,27,48,0.2) 0%, transparent 50%),
    radial-gradient(ellipse at 85% 60%, rgba(90,125,110,0.12) 0%, transparent 40%),
    radial-gradient(ellipse at 50% 100%, rgba(155,27,48,0.08) 0%, transparent 50%);
  pointer-events: none;
}

/* Decorative arcs inspired by CAMO site */
.hero__bg::before,
.hero__bg::after {
  content: "";
  position: absolute;
  border-radius: 50%;
  border: 1px solid rgba(255,180,180,0.08);
  pointer-events: none;
}

.hero__bg::before {
  width: 800px;
  height: 400px;
  bottom: -120px;
  left: -100px;
  transform: rotate(-8deg);
  box-shadow:
    0 -20px 0 rgba(255,180,180,0.04),
    0 -40px 0 rgba(255,180,180,0.03),
    0 -60px 0 rgba(255,180,180,0.02);
}

.hero__bg::after {
  width: 600px;
  height: 300px;
  top: -80px;
  right: -100px;
  transform: rotate(12deg);
  box-shadow:
    0 20px 0 rgba(255,180,180,0.04),
    0 40px 0 rgba(255,180,180,0.03);
}

.hero__content {
  position: relative;
  max-width: var(--max-width);
  margin: 0 auto;
}

.hero__eyebrow {
  margin: 0 0 20px;
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: rgba(255,255,255,0.55);
}

.hero h1 {
  margin: 0 0 28px;
  font-family: var(--font-heading);
  font-size: clamp(2.4rem, 5vw, 4.2rem);
  font-weight: 700;
  line-height: 1.08;
  color: var(--white);
  letter-spacing: -0.01em;
}

.hero h1 .dot {
  color: var(--crimson);
}

.hero__desc {
  max-width: 640px;
  margin: 0 0 40px;
  font-size: 1.05rem;
  line-height: 1.75;
  color: rgba(255,255,255,0.7);
}

.hero__desc strong {
  color: rgba(255,255,255,0.95);
  font-weight: 600;
}

.hero__stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 1px;
  background: rgba(255,255,255,0.08);
  border-radius: var(--radius-md);
  overflow: hidden;
  max-width: 900px;
}

.hero-stat {
  padding: 20px 22px;
  background: rgba(255,255,255,0.04);
  backdrop-filter: blur(10px);
}

.hero-stat__value {
  display: block;
  font-family: var(--font-heading);
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--white);
  line-height: 1;
  margin-bottom: 6px;
}

.hero-stat__label {
  font-size: 0.75rem;
  color: rgba(255,255,255,0.5);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

/* ============================================================
   FILTER BAR (Search + Tabs)
   ============================================================ */
.filterbar {
  position: sticky;
  top: 64px;
  z-index: 90;
  background: var(--white);
  border-bottom: 1px solid var(--gray-100);
  box-shadow: var(--shadow-sm);
}

.filterbar__inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 14px 32px;
  display: flex;
  align-items: center;
  gap: 20px;
}

.filterbar__search {
  position: relative;
  flex: 0 1 360px;
}

.filterbar__search-icon {
  position: absolute;
  left: 14px;
  top: 50%;
  transform: translateY(-50%);
  width: 16px;
  height: 16px;
  color: var(--gray-400);
  pointer-events: none;
}

.filterbar__search input {
  width: 100%;
  padding: 10px 14px 10px 40px;
  border: 1px solid var(--gray-200);
  border-radius: 99px;
  background: var(--gray-50);
  font-size: 0.88rem;
  color: var(--gray-800);
  outline: none;
  transition: all var(--transition);
}

.filterbar__search input:focus {
  border-color: var(--crimson);
  background: var(--white);
  box-shadow: 0 0 0 3px var(--crimson-light);
}

.filterbar__search input::placeholder {
  color: var(--gray-400);
}

.filterbar__tabs {
  display: flex;
  gap: 4px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  flex: 1;
}

.theme-tab {
  flex-shrink: 0;
  padding: 8px 18px;
  border: 1px solid var(--gray-200);
  border-radius: 99px;
  background: transparent;
  color: var(--gray-500);
  font-size: 0.82rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  cursor: pointer;
  transition: all var(--transition);
  white-space: nowrap;
}

.theme-tab:hover {
  color: var(--navy);
  border-color: var(--gray-400);
  background: var(--gray-50);
}

.theme-tab.is-active {
  color: var(--white);
  background: var(--crimson);
  border-color: var(--crimson);
  font-weight: 600;
}

/* ============================================================
   MAIN LAYOUT
   ============================================================ */
.main {
  padding: 32px;
}

.main__inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 260px minmax(0, 1fr);
  gap: 32px;
}

/* ============================================================
   SIDEBAR (Table of Contents)
   ============================================================ */
.sidebar__sticky {
  position: sticky;
  top: 140px;
  display: flex;
  flex-direction: column;
  gap: 16px;
  max-height: calc(100vh - 160px);
  overflow-y: auto;
  padding-right: 4px;
}

.sidebar__sticky::-webkit-scrollbar { width: 3px; }
.sidebar__sticky::-webkit-scrollbar-thumb { background: var(--gray-200); border-radius: 4px; }

.sidebar__heading {
  margin: 0;
  font-family: var(--font-heading);
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--navy);
  letter-spacing: 0.01em;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--crimson);
}

.sidebar__nav {
  display: flex;
  flex-direction: column;
  gap: 0;
}

/* Parent theme group in TOC */
.toc-group {
  margin-bottom: 4px;
}

.toc-group__label {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 10px;
  font-size: 0.76rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--crimson);
  cursor: pointer;
  border: none;
  background: transparent;
  width: 100%;
  text-align: left;
  transition: background var(--transition);
  border-radius: var(--radius-sm);
}

.toc-group__label:hover {
  background: var(--crimson-light);
}

.toc-group__label svg {
  width: 10px;
  height: 10px;
  flex-shrink: 0;
  transition: transform var(--transition);
  color: var(--gray-400);
}

.toc-group.is-open .toc-group__label svg {
  transform: rotate(90deg);
  color: var(--crimson);
}

.toc-group__items {
  display: none;
  flex-direction: column;
  padding-left: 6px;
  border-left: 2px solid var(--gray-100);
  margin-left: 14px;
}

.toc-group.is-open .toc-group__items {
  display: flex;
}

/* Subtopic items */
.sidebar__nav-item {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 6px 10px;
  border-radius: var(--radius-sm);
  text-decoration: none;
  color: var(--gray-600);
  font-size: 0.8rem;
  transition: all var(--transition);
  border: 1px solid transparent;
}

.sidebar__nav-item:hover {
  background: var(--crimson-light);
  color: var(--crimson);
  text-decoration: none;
  border-color: rgba(155,27,48,0.08);
}

.sidebar__nav-code {
  flex-shrink: 0;
  width: 24px;
  font-weight: 600;
  color: var(--crimson);
  font-size: 0.72rem;
}

.sidebar__nav-title {
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  flex: 1;
}

.sidebar__nav-count {
  margin-left: auto;
  flex-shrink: 0;
  font-size: 0.68rem;
  color: var(--gray-400);
  background: var(--gray-50);
  padding: 1px 7px;
  border-radius: 99px;
}

.sidebar__legend {
  padding: 16px;
  background: var(--white);
  border: 1px solid var(--gray-100);
  border-radius: var(--radius-md);
}

.sidebar__legend-title {
  margin: 0 0 10px;
  font-size: 0.72rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--gray-400);
}

.sidebar__legend-item {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.78rem;
  color: var(--gray-500);
  margin-bottom: 6px;
}

.sidebar__legend-item:last-child { margin-bottom: 0; }

.confidence-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  flex-shrink: 0;
}

.confidence-dot--high { background: var(--moss); }
.confidence-dot--medium { background: var(--gold); }

/* ============================================================
   CONTENT
   ============================================================ */
.results-summary {
  margin-bottom: 24px;
  font-size: 0.9rem;
  color: var(--gray-500);
}

.themes-container {
  display: flex;
  flex-direction: column;
  gap: 48px;
}

/* --- Theme Section --- */
.theme-section {
  scroll-margin-top: 160px;
}

.subtopic-card {
  scroll-margin-top: 160px;
}

.theme-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 28px;
  padding-bottom: 24px;
  border-bottom: 2px solid var(--gray-100);
}

.theme-header__left {}

.theme-kicker {
  display: inline-block;
  margin: 0 0 8px;
  padding: 4px 12px;
  background: var(--crimson);
  color: var(--white);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  border-radius: 3px;
}

.theme-header h2 {
  margin: 0 0 8px;
  font-family: var(--font-heading);
  font-size: clamp(1.8rem, 3vw, 2.4rem);
  font-weight: 700;
  color: var(--navy);
  line-height: 1.1;
}

.theme-header h2::after {
  content: ".";
  color: var(--crimson);
}

.theme-header__desc {
  margin: 0;
  max-width: 60ch;
  font-size: 0.95rem;
  color: var(--gray-500);
  line-height: 1.6;
  font-style: italic;
}

.theme-badge {
  flex-shrink: 0;
  text-align: center;
  padding: 16px 20px;
  background: var(--white);
  border: 1px solid var(--gray-100);
  border-radius: var(--radius-md);
}

.theme-badge__count {
  display: block;
  font-family: var(--font-heading);
  font-size: 2rem;
  font-weight: 700;
  color: var(--navy);
  line-height: 1;
}

.theme-badge__label {
  font-size: 0.72rem;
  color: var(--gray-400);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.subtopics-list {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

/* --- Subtopic Card --- */
.subtopic-card {
  background: var(--white);
  border: 1px solid var(--gray-100);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: box-shadow var(--transition);
}

.subtopic-card:hover {
  box-shadow: var(--shadow-md);
}

.subtopic-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 20px 24px;
  border-bottom: 1px solid var(--gray-50);
}

.subtopic-header__left {
  display: flex;
  align-items: center;
  gap: 14px;
  min-width: 0;
}

.subtopic-code {
  flex-shrink: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border-radius: var(--radius-sm);
  background: var(--crimson-light);
  color: var(--crimson);
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.04em;
}

.subtopic-header h3 {
  margin: 0;
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--navy);
  line-height: 1.25;
}

.subtopic-header h3::after {
  content: ".";
  color: var(--crimson);
}

.subtopic-pill {
  flex-shrink: 0;
  padding: 4px 14px;
  border-radius: 99px;
  background: var(--gray-50);
  color: var(--gray-500);
  font-size: 0.78rem;
  font-weight: 500;
}

.subtopic-body {
  padding: 0;
}

/* --- Question Accordion --- */
.question {
  border-top: 1px solid var(--gray-50);
}

.question:first-child {
  border-top: none;
}

.question__trigger {
  display: grid;
  grid-template-columns: auto 1fr auto auto;
  gap: 12px;
  align-items: center;
  width: 100%;
  padding: 16px 24px;
  border: none;
  background: transparent;
  cursor: pointer;
  text-align: left;
  transition: background var(--transition);
}

.question__trigger:hover {
  background: var(--gray-50);
}

.question__code {
  font-size: 0.76rem;
  font-weight: 700;
  color: var(--crimson);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  white-space: nowrap;
}

.question__text {
  margin: 0;
  font-size: 0.92rem;
  color: var(--gray-600);
  line-height: 1.55;
}

.question__count {
  font-size: 0.78rem;
  color: var(--gray-400);
  white-space: nowrap;
}

.question__arrow {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--gray-50);
  color: var(--gray-400);
  font-size: 0.85rem;
  transition: all var(--transition);
  flex-shrink: 0;
}

.question.is-open .question__arrow {
  background: var(--crimson-light);
  color: var(--crimson);
  transform: rotate(180deg);
}

.question__papers {
  display: none;
  padding: 0 24px 20px;
}

.question.is-open .question__papers {
  display: block;
}

/* Empty question state */
.question__empty {
  padding: 20px;
  text-align: center;
  font-size: 0.85rem;
  color: var(--gray-400);
  font-style: italic;
  background: var(--gray-50);
  border-radius: var(--radius-sm);
}

/* --- Paper Grid --- */
.paper-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
}

/* --- Paper Card --- */
.paper-card {
  display: flex;
  flex-direction: column;
  border: 1px solid var(--gray-100);
  border-radius: var(--radius-md);
  overflow: hidden;
  background: var(--off-white);
  transition: all var(--transition);
}

.paper-card:hover {
  border-color: var(--gray-200);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

/* Slide preview area */
.paper-card__preview {
  position: relative;
  height: 200px;
  background: var(--gray-50);
  cursor: pointer;
  overflow: hidden;
}

.paper-card__preview iframe {
  width: 100%;
  height: 100%;
  border: none;
  pointer-events: none;
  background: white;
}

.paper-card__preview-overlay {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(27,42,74,0.0);
  transition: background var(--transition);
}

.paper-card__preview:hover .paper-card__preview-overlay {
  background: rgba(27,42,74,0.4);
}

.paper-card__preview-btn {
  opacity: 0;
  transform: translateY(8px);
  transition: all var(--transition);
  padding: 10px 20px;
  border: none;
  border-radius: var(--radius-sm);
  background: var(--crimson);
  color: white;
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  letter-spacing: 0.02em;
}

.paper-card__preview:hover .paper-card__preview-btn {
  opacity: 1;
  transform: translateY(0);
}

.paper-card__preview-empty {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100%;
  color: var(--gray-400);
  font-size: 0.82rem;
}

/* Paper card info */
.paper-card__info {
  flex: 1;
  display: flex;
  flex-direction: column;
  padding: 16px 18px;
}

.paper-card__meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  margin-bottom: 8px;
}

.paper-card__id {
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--gray-400);
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.paper-card__confidence {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  font-size: 0.7rem;
  font-weight: 500;
  padding: 2px 8px;
  border-radius: 99px;
}

.paper-card__confidence--high {
  background: rgba(90,125,110,0.12);
  color: var(--moss);
}

.paper-card__confidence--medium {
  background: rgba(196,151,59,0.15);
  color: #8B6914;
}

.paper-card__title {
  margin: 0 0 12px;
  font-size: 0.92rem;
  font-weight: 600;
  color: var(--navy);
  line-height: 1.45;
  flex: 1;
}

.paper-card__actions {
  display: flex;
  gap: 8px;
  margin-top: auto;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 8px 16px;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-sm);
  background: var(--white);
  color: var(--gray-600);
  font-size: 0.8rem;
  font-weight: 500;
  text-decoration: none;
  cursor: pointer;
  transition: all var(--transition);
  white-space: nowrap;
}

.btn:hover {
  border-color: var(--crimson);
  color: var(--crimson);
  text-decoration: none;
}

.btn--primary {
  border-color: var(--crimson);
  background: var(--crimson);
  color: var(--white);
}

.btn--primary:hover {
  background: var(--crimson-dark);
  border-color: var(--crimson-dark);
  color: var(--white);
}

.btn:disabled,
.btn.is-disabled {
  opacity: 0.4;
  pointer-events: none;
}

.btn svg {
  width: 14px;
  height: 14px;
}

/* ============================================================
   MODAL
   ============================================================ */
.modal {
  position: fixed;
  inset: 0;
  z-index: 200;
  display: none;
}

.modal.is-open { display: flex; align-items: center; justify-content: center; }

.modal__backdrop {
  position: absolute;
  inset: 0;
  background: rgba(17,29,51,0.6);
  backdrop-filter: blur(8px);
}

.modal__dialog {
  position: relative;
  display: flex;
  flex-direction: column;
  width: min(1100px, calc(100vw - 48px));
  height: min(88vh, 860px);
  border-radius: var(--radius-lg);
  background: var(--white);
  box-shadow: var(--shadow-xl);
  overflow: hidden;
}

.modal__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 20px 28px;
  border-bottom: 1px solid var(--gray-100);
  flex-shrink: 0;
}

.modal__eyebrow {
  margin: 0 0 4px;
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--crimson);
}

.modal__title {
  margin: 0;
  font-family: var(--font-heading);
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--navy);
  line-height: 1.3;
}

.modal__close {
  width: 40px;
  height: 40px;
  border: none;
  border-radius: 50%;
  background: var(--gray-50);
  color: var(--gray-500);
  font-size: 1.4rem;
  cursor: pointer;
  transition: all var(--transition);
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}

.modal__close:hover {
  background: var(--crimson-light);
  color: var(--crimson);
}

.modal__body {
  flex: 1;
  min-height: 0;
  background: var(--gray-50);
}

/* ============================================================
   FOOTER
   ============================================================ */
.footer {
  background: var(--navy-deep);
  color: rgba(255,255,255,0.5);
  padding: 48px 32px;
  margin-top: 48px;
}

.footer__inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.footer__brand {
  display: flex;
  align-items: center;
  gap: 16px;
}

.footer__logo {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--white);
  letter-spacing: 0.06em;
}

.footer__brand p {
  margin: 0;
  font-size: 0.78rem;
  line-height: 1.5;
  border-left: 1px solid rgba(255,255,255,0.15);
  padding-left: 16px;
}

.footer__copy {
  margin: 0;
  font-size: 0.82rem;
  font-style: italic;
}

/* ============================================================
   EMPTY STATE
   ============================================================ */
.empty-state {
  text-align: center;
  padding: 64px 24px;
  color: var(--gray-400);
  font-size: 0.95rem;
}

/* Hidden utility */
[hidden] { display: none !important; }

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media (max-width: 1100px) {
  .main__inner {
    grid-template-columns: 1fr;
  }

  .sidebar {
    order: -1;
  }

  .sidebar__sticky {
    position: static;
    max-height: none;
  }

  .sidebar__nav {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 4px;
  }

  .toc-group {
    margin-bottom: 0;
  }

  .toc-group__items {
    display: flex !important;
    margin-left: 0;
    padding-left: 0;
    border-left: none;
  }

  .paper-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  .hero {
    padding: 56px 20px 36px;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .hero__stats {
    grid-template-columns: repeat(3, 1fr);
  }

  .main {
    padding: 20px 16px;
  }

  .theme-tabs__inner {
    padding: 0 16px;
  }

  .theme-header {
    flex-direction: column;
  }

  .paper-grid {
    grid-template-columns: 1fr !important;
  }

  .filterbar__inner {
    flex-direction: column;
    gap: 10px;
  }

  .filterbar__search {
    flex: 1 1 100%;
    width: 100%;
  }

  .filterbar__tabs {
    width: 100%;
  }

  .question__trigger {
    grid-template-columns: 1fr auto;
    padding: 14px 18px;
  }

  .question__code {
    grid-column: 1 / -1;
  }

  .subtopic-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 10px;
    padding: 16px 18px;
  }

  .question__papers {
    padding: 0 18px 16px;
  }

  .footer__inner {
    flex-direction: column;
    text-align: center;
  }

  .footer__brand {
    flex-direction: column;
  }

  .footer__brand p {
    border-left: none;
    padding-left: 0;
  }

  .topbar__sub {
    display: none;
  }
}

@media (max-width: 480px) {
  .hero__stats {
    grid-template-columns: repeat(2, 1fr);
  }

  .modal__dialog {
    width: calc(100vw - 16px);
    height: calc(100vh - 16px);
    border-radius: var(--radius-md);
  }
}