:root {
  --black: #0a0a0a;
  --white: #f8f7f4;
  --yellow: #f5c518;
  --yellow-dim: #f5c51820;
  --gray: #888;
  --surface: #1a1a10;
  --surface2: #202020;
  --gray-light: #141414;
  --gray-border: #252525;
  --nav-bg: rgba(10,10,10,0.85);
  --card-bg: #1a1a10;
  --card-hover: #202020;
  --badge-text: #0a0a0a;
  --serif: 'Instrument Serif', Georgia, serif;
  --sans: 'DM Sans', system-ui, sans-serif;
  --accent-physics: #3b82f6;
  --accent-chemistry: #22c55e;
  --accent-maths: #a855f7;
  --accent-red: #e84545;
  --accent-cyan: #06b6d4;
  --accent-teal: #14b8a6;
  --success: #22c55e;
  --danger: #e84545;
  /* Text size scale — adjustable from admin settings */
  --text-scale: 1;
}

[data-theme="light"] {
  --black: #f5f4f0;
  --white: #1a1a1a;
  --yellow: #b8930a;
  --yellow-dim: #b8930a12;
  --gray: #555;
  --surface: #ffffff;
  --surface2: #f0eeea;
  --gray-light: #eae8e4;
  --gray-border: #d4d2cd;
  --nav-bg: rgba(245,244,240,0.9);
  --card-bg: #ffffff;
  --card-hover: #f0eeea;
  --badge-text: #ffffff;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  background: var(--black);
  color: var(--white);
  font-family: var(--sans);
  font-weight: 300;
  font-size: calc(1rem * var(--text-scale, 1));
  line-height: 1.7;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

::selection { background: var(--yellow); color: var(--black); }

a { color: inherit; text-decoration: none; }
img { max-width: 100%; }

/* ─── NAV ─── */
nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  padding: 1.5rem 3rem;
  display: flex; align-items: center; justify-content: space-between;
  backdrop-filter: blur(20px);
  background: var(--nav-bg);
  border-bottom: 1px solid var(--gray-border);
  transition: padding 0.4s ease;
}
nav.scrolled { padding: 0.8rem 3rem; }

.nav-logo {
  display: flex;
  flex-direction: row;
  align-items: center;
  gap: 0.65rem;
  line-height: 1;
}
.nav-logo-icon {
  width: 34px; height: 34px; flex-shrink: 0;
  display: block;
  transition: transform 0.4s cubic-bezier(.2,.8,.2,1), filter 0.3s;
}
.nav-logo:hover .nav-logo-icon { transform: rotate(60deg); filter: drop-shadow(0 0 6px rgba(245,197,24,0.45)); }
.nav-logo-text { display: flex; flex-direction: column; align-items: flex-start; line-height: 1; }
.nav-logo-brand {
  font-family: var(--sans);
  font-weight: 700;
  font-size: 1.42rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--yellow);
  text-decoration: none;
  display: block;
}
.nav-logo-brand span { color: var(--white); font-weight: 300; }
.nav-logo-tag {
  display: block;
  font-size: 0.55rem;
  font-weight: 400;
  letter-spacing: 0.08em;
  color: var(--gray);
  text-transform: none;
  margin-top: 0.35rem;
  white-space: nowrap;
}
.nav-logo-tag a { color: var(--yellow); text-decoration: none; border-bottom: 1px dotted var(--yellow); }
.nav-logo-tag a:hover { color: #fff; border-bottom-color: #fff; }

.nav-links { display: flex; gap: 2.5rem; align-items: center; }
.nav-links a {
  color: var(--gray);
  text-decoration: none;
  font-size: 0.8rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  transition: color 0.3s;
}
.nav-links a:hover, .nav-links a.active { color: var(--yellow); }

.nav-right { display: flex; align-items: center; gap: 1rem; }

.nav-cta {
  padding: 0.55rem 1.5rem;
  border: 1px solid var(--yellow);
  color: var(--yellow);
  text-decoration: none;
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  transition: all 0.3s;
  display: inline-block;
}
.nav-cta:hover { background: var(--yellow); color: var(--black); }

/* Theme toggle — intentionally bright to help users discover the light/dark option.
 * In DARK mode → shows a bright yellow ☀ "Sun" on a dim yellow bg, to signal "tap
 *                for light theme".
 * In LIGHT mode → shows a white ☾ "Moon" on solid black, inverted from the page
 *                 so it's always visible and unmistakable as a toggle.
 */
.theme-toggle {
  border: 1px solid var(--yellow);
  width: 40px; height: 40px;
  font-size: 1.1rem;
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  transition: transform 0.25s cubic-bezier(.2,.8,.2,1), background 0.25s, color 0.25s, box-shadow 0.25s;
  flex-shrink: 0;
  border-radius: 50%;
}
/* Dark theme → bright yellow Sun */
[data-theme="dark"] .theme-toggle,
.theme-toggle { /* default falls through to dark */
  background: rgba(245,197,24,0.12);
  color: var(--yellow, #f5c518);
  box-shadow: 0 0 0 0 rgba(245,197,24,0), inset 0 0 14px rgba(245,197,24,0.18);
}
[data-theme="dark"] .theme-toggle:hover,
.theme-toggle:hover {
  background: var(--yellow, #f5c518);
  color: #0a0a0a;
  transform: rotate(25deg) scale(1.05);
  box-shadow: 0 0 18px rgba(245,197,24,0.55), 0 0 0 2px rgba(245,197,24,0.25);
}
/* Light theme → inverted Moon: white icon on pure black circle */
[data-theme="light"] .theme-toggle {
  background: #0a0a0a;
  color: #ffffff;
  border-color: #0a0a0a;
  box-shadow: 0 2px 10px rgba(0,0,0,0.18);
}
[data-theme="light"] .theme-toggle:hover {
  background: #1a1a1a;
  transform: rotate(-20deg) scale(1.05);
  box-shadow: 0 3px 16px rgba(0,0,0,0.3), 0 0 0 2px rgba(0,0,0,0.08);
}

.nav-mobile-toggle {
  display: none;
  background: none;
  border: 1px solid var(--gray-border);
  color: var(--white);
  width: 40px; height: 40px;
  font-size: 1.2rem;
  cursor: pointer;
  align-items: center; justify-content: center;
}

.mobile-menu {
  display: none;
  position: fixed; top: 0; left: 0; right: 0; bottom: 0;
  background: var(--black);
  z-index: 200;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 2rem;
  opacity: 0;
  transition: opacity 0.3s;
}
.mobile-menu.open { display: flex; opacity: 0.97; }
.mobile-menu a {
  color: var(--white);
  font-size: 1.5rem;
  font-family: var(--serif);
  text-decoration: none;
  transition: color 0.3s;
}
.mobile-menu a:hover { color: var(--yellow); }
.mobile-menu-close {
  position: absolute; top: 1.5rem; right: 1.5rem;
  background: none; border: 1px solid var(--gray-border);
  color: var(--white); width: 40px; height: 40px;
  font-size: 1.2rem; cursor: pointer;
  display: flex; align-items: center; justify-content: center;
}

/* ─── HERO ─── */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding: 8rem 3rem 6rem;
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  top: -20%; right: -10%;
  width: 60%; height: 80%;
  background: radial-gradient(ellipse, var(--yellow-dim) 0%, transparent 70%);
  pointer-events: none;
}
.hero-content {
  max-width: 800px;
  position: relative;
  z-index: 2;
}
.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.4rem 1rem;
  border: 1px solid var(--gray-border);
  font-size: 0.7rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--gray);
  margin-bottom: 2rem;
  animation: fadeUp 0.8s ease;
}
.hero-badge .pulse {
  width: 6px; height: 6px;
  background: var(--yellow);
  border-radius: 50%;
  animation: pulse 2s infinite;
}
.hero h1 {
  font-family: var(--serif);
  font-weight: 400;
  font-size: clamp(3.5rem, 8vw, 7.5rem);
  line-height: 1.05;
  margin-bottom: 1.5rem;
  animation: fadeUp 0.8s ease 0.2s both;
}
.hero h1 em {
  font-style: italic;
  color: var(--yellow);
}
.hero-sub {
  color: var(--gray);
  font-size: 1.1rem;
  max-width: 520px;
  margin-bottom: 2.5rem;
  animation: fadeUp 0.8s ease 0.4s both;
}
.hero-actions {
  display: flex;
  gap: 1.5rem;
  align-items: center;
  flex-wrap: wrap;
  animation: fadeUp 0.8s ease 0.6s both;
}

/* Stats row */
.hero-stats {
  display: flex;
  gap: 3rem;
  margin-top: 4rem;
  padding-top: 3rem;
  border-top: 1px solid var(--gray-border);
  animation: fadeUp 0.8s ease 0.8s both;
}
.hero-stat-number {
  font-family: var(--serif);
  font-size: 2.5rem;
  color: var(--yellow);
  line-height: 1.1;
}
.hero-stat-label {
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--gray);
  margin-top: 0.3rem;
}

/* ─── BUTTONS ─── */
.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.85rem 2rem;
  background: var(--yellow);
  color: var(--badge-text);
  font-family: var(--sans);
  font-size: 0.8rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  border: none;
  cursor: pointer;
  transition: all 0.3s;
  text-decoration: none;
}
.btn-primary:hover { filter: brightness(1.1); transform: translateY(-1px); }

.btn-ghost {
  color: var(--white);
  font-size: 0.8rem;
  font-weight: 400;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  text-decoration: none;
  border-bottom: 1px solid var(--gray-border);
  padding-bottom: 0.3rem;
  transition: all 0.3s;
  background: none;
  border-top: none;
  border-left: none;
  border-right: none;
  cursor: pointer;
}
.btn-ghost:hover { border-bottom-color: var(--yellow); color: var(--yellow); }

.btn-outline {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.7rem 1.5rem;
  border: 1px solid var(--gray-border);
  background: transparent;
  color: var(--white);
  font-family: var(--sans);
  font-size: 0.8rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  cursor: pointer;
  transition: all 0.3s;
  text-decoration: none;
}
.btn-outline:hover { border-color: var(--yellow); color: var(--yellow); }

.btn-small {
  padding: 0.5rem 1rem;
  font-size: 0.7rem;
}

.btn-danger { border-color: var(--danger); color: var(--danger); }
.btn-danger:hover { background: var(--danger); color: var(--white); }

/* ─── SECTIONS ─── */
.section {
  padding: 6rem 3rem;
}
.section-label {
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.2em;
  color: var(--yellow);
  margin-bottom: 1rem;
}
.section-title {
  font-family: var(--serif);
  font-weight: 400;
  font-size: clamp(2rem, 4vw, 3.5rem);
  line-height: 1.15;
  margin-bottom: 1rem;
}
.section-desc {
  color: var(--gray);
  max-width: 560px;
  font-size: 1rem;
  line-height: 1.8;
  margin-bottom: 3rem;
}
.section-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  flex-wrap: wrap;
  gap: 1.5rem;
  margin-bottom: 3rem;
}

/* ─── CARDS ─── */
.card {
  background: var(--card-bg);
  border: 1px solid var(--gray-border);
  padding: 2rem;
  transition: all 0.3s;
  position: relative;
  overflow: hidden;
}
.card:hover {
  background: var(--card-hover);
  box-shadow: inset 0 0 0 1px var(--yellow-dim);
}
.card-icon {
  width: 48px; height: 48px;
  border: 1px solid var(--gray-border);
  display: flex; align-items: center; justify-content: center;
  font-size: 1.3rem;
  margin-bottom: 1.5rem;
  color: var(--yellow);
  transition: all 0.3s;
}
.card:hover .card-icon {
  background: var(--yellow);
  color: var(--black);
  border-color: var(--yellow);
}
.card h3 {
  font-family: var(--serif);
  font-size: 1.3rem;
  font-weight: 400;
  margin-bottom: 0.5rem;
}
.card p {
  color: var(--gray);
  font-size: 0.9rem;
  line-height: 1.6;
}
.card-tag {
  display: inline-block;
  padding: 0.2rem 0.6rem;
  border: 1px solid var(--yellow-dim);
  font-size: 0.65rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--yellow);
  margin-bottom: 1rem;
}

/* ─── GRID LAYOUTS ─── */
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1px; background: var(--gray-border); }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1px; background: var(--gray-border); }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 1px; background: var(--gray-border); }
.grid-2 > *, .grid-3 > *, .grid-4 > * { background: var(--black); }

.flex-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 1.5rem; }

/* ─── FEATURE CARDS (Homepage) ─── */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1px;
  background: var(--gray-border);
}
.feature-card {
  background: var(--black);
  padding: 3rem 2.5rem;
  transition: all 0.3s;
  position: relative;
}
.feature-card:hover {
  background: var(--card-hover);
  box-shadow: inset 0 0 0 1px var(--yellow-dim);
}
.feature-card .icon {
  width: 48px; height: 48px;
  border: 1px solid var(--gray-border);
  display: flex; align-items: center; justify-content: center;
  font-size: 1.3rem;
  margin-bottom: 1.5rem;
  color: var(--yellow);
  transition: all 0.3s;
}
.feature-card:hover .icon {
  background: var(--yellow);
  color: var(--black);
  border-color: var(--yellow);
}
.feature-card h3 {
  font-family: var(--serif);
  font-size: 1.5rem;
  font-weight: 400;
  margin-bottom: 0.8rem;
}
.feature-card p {
  color: var(--gray);
  font-size: 0.92rem;
  line-height: 1.7;
}
.feature-card .learn-more {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  color: var(--yellow);
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-top: 1.5rem;
  transition: gap 0.3s;
}
.feature-card:hover .learn-more { gap: 0.6rem; }

/* ─── AI PROFILES SECTION ─── */
.ai-profiles-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}
.ai-profile-card {
  background: var(--card-bg);
  border: 1px solid var(--gray-border);
  padding: 2rem;
  text-align: center;
  transition: all 0.3s;
  cursor: pointer;
  text-decoration: none;
  display: block;
}
.ai-profile-card:hover {
  border-color: var(--yellow);
  transform: translateY(-4px);
  box-shadow: 0 8px 32px rgba(0,0,0,0.3);
}
.ai-profile-avatar {
  width: 80px; height: 80px;
  border-radius: 50%;
  margin: 0 auto 1rem;
  display: flex; align-items: center; justify-content: center;
  font-size: 2rem;
  border: 2px solid var(--gray-border);
  transition: border-color 0.3s;
}
.ai-profile-card:hover .ai-profile-avatar { border-color: var(--yellow); }
.ai-profile-card h3 {
  font-family: var(--serif);
  font-size: 1.3rem;
  font-weight: 400;
  margin-bottom: 0.3rem;
}
.ai-profile-card .source {
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--yellow);
  margin-bottom: 0.8rem;
}
.ai-profile-card .tagline {
  color: var(--gray);
  font-size: 0.85rem;
  font-style: italic;
}

/* ─── VIDEO CARDS ─── */
.video-card {
  background: var(--card-bg);
  border: 1px solid var(--gray-border);
  overflow: hidden;
  transition: all 0.3s;
  cursor: pointer;
  text-decoration: none;
  display: block;
}
.video-card:hover {
  border-color: var(--yellow);
  transform: translateY(-2px);
}
.video-thumb {
  width: 100%;
  aspect-ratio: 16/9;
  background: var(--gray-light);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2.5rem;
  color: var(--gray);
  position: relative;
  overflow: hidden;
}
.video-thumb .play-icon {
  width: 50px; height: 50px;
  background: var(--yellow);
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  color: var(--black);
  font-size: 1.2rem;
  transition: transform 0.3s;
}
.video-card:hover .play-icon { transform: scale(1.1); }
.video-info {
  padding: 1.2rem;
}
.video-info h4 {
  font-family: var(--serif);
  font-size: 1.05rem;
  font-weight: 400;
  margin-bottom: 0.4rem;
}
.video-meta {
  display: flex;
  gap: 1rem;
  font-size: 0.75rem;
  color: var(--gray);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.video-meta .difficulty {
  padding: 0.15rem 0.5rem;
  border: 1px solid currentColor;
  font-size: 0.65rem;
}
.difficulty-easy { color: var(--success); }
.difficulty-medium { color: var(--yellow); }
.difficulty-hard { color: var(--danger); }

/* ─── TEST CARDS ─── */
.test-card {
  background: var(--card-bg);
  border: 1px solid var(--gray-border);
  padding: 2rem;
  transition: all 0.3s;
}
.test-card:hover {
  border-color: var(--yellow);
  background: var(--card-hover);
}
.test-card h3 {
  font-family: var(--serif);
  font-size: 1.2rem;
  font-weight: 400;
  margin-bottom: 0.5rem;
}
.test-card p {
  color: var(--gray);
  font-size: 0.85rem;
  margin-bottom: 1rem;
}
.test-meta {
  display: flex;
  gap: 1.5rem;
  margin-bottom: 1.5rem;
}
.test-meta-item {
  font-size: 0.75rem;
  color: var(--gray);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.test-meta-item strong { color: var(--white); display: block; font-size: 1rem; font-weight: 500; }
.intensity-badge {
  display: inline-block;
  padding: 0.2rem 0.6rem;
  font-size: 0.65rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  border: 1px solid;
  margin-bottom: 1rem;
}
.intensity-easy { color: var(--success); border-color: var(--success); }
.intensity-medium { color: var(--yellow); border-color: var(--yellow); }
.intensity-hard { color: var(--danger); border-color: var(--danger); }
.intensity-jee_main { color: var(--accent-physics); border-color: var(--accent-physics); }
.intensity-jee_advanced { color: var(--accent-maths); border-color: var(--accent-maths); }

/* ─── TUTOR CARDS ─── */
.tutor-card {
  background: var(--card-bg);
  border: 1px solid var(--gray-border);
  padding: 2rem;
  display: flex;
  gap: 1.5rem;
  transition: all 0.3s;
}
.tutor-card:hover {
  border-color: var(--yellow);
  background: var(--card-hover);
}
.tutor-avatar {
  width: 64px; height: 64px;
  border-radius: 50%;
  background: var(--gray-light);
  border: 2px solid var(--gray-border);
  display: flex; align-items: center; justify-content: center;
  font-size: 1.5rem;
  flex-shrink: 0;
}
.tutor-info { flex: 1; }
.tutor-info h3 {
  font-family: var(--serif);
  font-size: 1.2rem;
  font-weight: 400;
  margin-bottom: 0.2rem;
}
.tutor-info .qualifications {
  font-size: 0.75rem;
  color: var(--gray);
  margin-bottom: 0.5rem;
}
.tutor-info .bio {
  font-size: 0.85rem;
  color: var(--gray);
  margin-bottom: 0.8rem;
  line-height: 1.5;
}
.tutor-stats {
  display: flex;
  gap: 1.5rem;
  margin-bottom: 1rem;
}
.tutor-stat {
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--gray);
}
.tutor-stat strong { color: var(--yellow); font-size: 0.9rem; display: block; }
.online-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  padding: 0.2rem 0.6rem;
  border: 1px solid var(--success);
  color: var(--success);
}
.online-badge .dot {
  width: 6px; height: 6px;
  background: var(--success);
  border-radius: 50%;
  animation: pulse 2s infinite;
}
.offline-badge {
  display: inline-flex;
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  padding: 0.2rem 0.6rem;
  border: 1px solid var(--gray);
  color: var(--gray);
}

/* ─── CHAT INTERFACE ─── */
.chat-container {
  display: flex;
  flex-direction: column;
  height: calc(100vh - 80px);
  margin-top: 80px;
}
.chat-header {
  padding: 1.5rem 2rem;
  border-bottom: 1px solid var(--gray-border);
  display: flex;
  align-items: center;
  gap: 1rem;
  background: var(--card-bg);
}
.chat-header-avatar {
  width: 48px; height: 48px;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.3rem;
  border: 2px solid var(--yellow);
}
.chat-header h2 {
  font-family: var(--serif);
  font-size: 1.3rem;
  font-weight: 400;
}
.chat-header .source-tag {
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--yellow);
}
.chat-messages {
  flex: 1;
  overflow-y: auto;
  padding: 2rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}
.chat-message {
  max-width: 70%;
  padding: 1rem 1.5rem;
  line-height: 1.6;
  font-size: 0.9rem;
}
.chat-message.student {
  align-self: flex-end;
  background: var(--yellow);
  color: var(--black);
}
.chat-message.ai {
  align-self: flex-start;
  background: var(--card-bg);
  border: 1px solid var(--gray-border);
}
.chat-message.ai p { margin: 0.4rem 0; }
.chat-message.ai ul, .chat-message.ai ol { margin: 0.4rem 0; padding-left: 1.5rem; }
.chat-message.ai code { background: rgba(255,255,255,0.06); padding: 0.1rem 0.3rem; font-size: 0.85em; border-radius: 2px; }
.chat-message.ai pre { background: rgba(0,0,0,0.3); padding: 0.8rem; overflow-x: auto; margin: 0.5rem 0; border-radius: 4px; }
.chat-message.ai pre code { background: none; padding: 0; }
.chat-message.ai .katex-display { margin: 0.8rem 0; overflow-x: auto; }
.chat-message.ai h1, .chat-message.ai h2, .chat-message.ai h3 { font-size: 1rem; font-weight: 600; margin: 0.6rem 0 0.3rem; }
.chat-input-bar {
  padding: 1.5rem 2rem;
  border-top: 1px solid var(--gray-border);
  display: flex;
  gap: 1rem;
  background: var(--card-bg);
}
.chat-input {
  flex: 1;
  padding: 0.8rem 1.2rem;
  background: var(--black);
  border: 1px solid var(--gray-border);
  color: var(--white);
  font-family: var(--sans);
  font-size: 0.9rem;
  outline: none;
  transition: border-color 0.3s;
}
.chat-input:focus { border-color: var(--yellow); }
.chat-input::placeholder { color: var(--gray); }

/* ─── TEST TAKING INTERFACE ─── */
.test-interface {
  max-width: 800px;
  margin: 0 auto;
  padding: 2rem 0;
}
.test-progress {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 2rem;
  padding: 1rem 1.5rem;
  background: var(--card-bg);
  border: 1px solid var(--gray-border);
}
.test-progress .timer {
  font-family: var(--sans);
  font-size: 1.2rem;
  font-weight: 500;
  color: var(--yellow);
}
.question-card {
  background: var(--card-bg);
  border: 1px solid var(--gray-border);
  padding: 2.5rem;
  margin-bottom: 1.5rem;
}
.question-number {
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--yellow);
  margin-bottom: 1rem;
}
.question-text {
  font-size: 1.05rem;
  line-height: 1.7;
  margin-bottom: 2rem;
}
.options-list {
  display: flex;
  flex-direction: column;
  gap: 0.8rem;
}
.option-btn {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 1rem 1.5rem;
  background: var(--black);
  border: 1px solid var(--gray-border);
  color: var(--white);
  font-family: var(--sans);
  font-size: 0.9rem;
  cursor: pointer;
  transition: all 0.3s;
  text-align: left;
  width: 100%;
}
.option-btn:hover { border-color: var(--yellow); }
.option-btn.selected { border-color: var(--yellow); background: var(--yellow-dim); }
.option-btn.correct { border-color: var(--success); background: rgba(34,197,94,0.1); color: var(--success); }
.option-btn.wrong { border-color: var(--danger); background: rgba(232,69,69,0.1); color: var(--danger); }
.option-label {
  width: 28px; height: 28px;
  border: 1px solid var(--gray-border);
  display: flex; align-items: center; justify-content: center;
  font-size: 0.75rem;
  font-weight: 500;
  flex-shrink: 0;
  transition: all 0.3s;
}
.option-btn.selected .option-label { background: var(--yellow); color: var(--black); border-color: var(--yellow); }
.explanation-box {
  margin-top: 1rem;
  padding: 1rem 1.5rem;
  background: var(--gray-light);
  border-left: 3px solid var(--yellow);
  font-size: 0.85rem;
  color: var(--gray);
  line-height: 1.6;
  display: none;
}
.explanation-box.visible { display: block; }

/* ─── RESULTS ─── */
.results-card {
  background: var(--card-bg);
  border: 1px solid var(--gray-border);
  padding: 3rem;
  text-align: center;
}
.results-score {
  font-family: var(--serif);
  font-size: 4rem;
  color: var(--yellow);
  line-height: 1.1;
}
.results-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--gray);
  margin-top: 0.5rem;
}

/* ─── FILTER BAR ─── */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 2rem;
}
.filter-btn {
  padding: 0.4rem 1rem;
  border: 1px solid var(--gray-border);
  background: transparent;
  color: var(--gray);
  font-family: var(--sans);
  font-size: 0.75rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  cursor: pointer;
  transition: all 0.3s;
}
.filter-btn:hover, .filter-btn.active {
  border-color: var(--yellow);
  color: var(--yellow);
}

/* ─── TESTIMONIALS / SOCIAL PROOF ─── */
.testimonial-card {
  background: var(--card-bg);
  border: 1px solid var(--gray-border);
  padding: 2.5rem;
  transition: all 0.3s;
}
.testimonial-card:hover { background: var(--card-hover); }
.testimonial-card .quote {
  font-family: var(--serif);
  font-size: 1.1rem;
  font-style: italic;
  line-height: 1.6;
  margin-bottom: 1.5rem;
}
.testimonial-card .author {
  font-size: 0.85rem;
  font-weight: 500;
}
.testimonial-card .author-role {
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--yellow);
}

/* ─── DASHBOARD ─── */
.dashboard-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  background: var(--gray-border);
  margin-bottom: 3rem;
}
.dashboard-stat {
  background: var(--black);
  padding: 2rem;
  text-align: center;
}
.dashboard-stat .value {
  font-family: var(--serif);
  font-size: 2.5rem;
  color: var(--yellow);
  line-height: 1.1;
}
.dashboard-stat .label {
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--gray);
  margin-top: 0.5rem;
}

/* ─── LOGIN / REGISTER ─── */
.auth-container {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 2rem;
}
.auth-card {
  background: var(--card-bg);
  border: 1px solid var(--gray-border);
  padding: 3rem;
  width: 100%;
  max-width: 420px;
}
.auth-card h2 {
  font-family: var(--serif);
  font-size: 2rem;
  font-weight: 400;
  margin-bottom: 0.5rem;
}
.auth-card .subtitle {
  color: var(--gray);
  font-size: 0.9rem;
  margin-bottom: 2rem;
}
.form-group {
  margin-bottom: 1.5rem;
}
.form-group label {
  display: block;
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--gray);
  margin-bottom: 0.5rem;
}
.form-group input, .form-group select, .form-group textarea {
  width: 100%;
  padding: 0.8rem 1rem;
  background: var(--black);
  border: 1px solid var(--gray-border);
  color: var(--white);
  font-family: var(--sans);
  font-size: 0.9rem;
  outline: none;
  transition: border-color 0.3s;
}
.form-group input:focus, .form-group select:focus, .form-group textarea:focus {
  border-color: var(--yellow);
}
.form-group textarea { min-height: 100px; resize: vertical; }
.form-error {
  color: var(--danger);
  font-size: 0.8rem;
  margin-top: 0.5rem;
  display: none;
}
.form-toggle {
  text-align: center;
  margin-top: 1.5rem;
  font-size: 0.85rem;
  color: var(--gray);
}
.form-toggle a { color: var(--yellow); text-decoration: underline; }

/* ─── ADMIN ─── */
.admin-layout {
  display: flex;
  min-height: 100vh;
  margin-top: 0;
}
.admin-sidebar {
  width: 240px;
  background: var(--card-bg);
  border-right: 1px solid var(--gray-border);
  padding: 5rem 0 2rem;
  flex-shrink: 0;
}
.admin-sidebar a {
  display: block;
  padding: 0.8rem 1.5rem;
  font-size: 0.8rem;
  color: var(--gray);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  transition: all 0.3s;
  border-left: 2px solid transparent;
}
.admin-sidebar a:hover, .admin-sidebar a.active {
  color: var(--yellow);
  background: var(--yellow-dim);
  border-left-color: var(--yellow);
}
.admin-content {
  flex: 1;
  padding: 6rem 3rem 3rem;
  overflow-y: auto;
}

/* ─── TABLE ─── */
.data-table {
  width: 100%;
  border-collapse: collapse;
  border: 1px solid var(--gray-border);
}
.data-table th {
  background: var(--card-bg);
  padding: 0.8rem 1rem;
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--gray);
  text-align: left;
  border-bottom: 1px solid var(--gray-border);
}
.data-table td {
  padding: 0.8rem 1rem;
  font-size: 0.85rem;
  border-bottom: 1px solid var(--gray-border);
}
.data-table tr:hover { background: var(--card-hover); }

/* ─── MODAL (TRAKR slide-from-right pattern) ─── */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.8);
  backdrop-filter: blur(8px);
  z-index: 200;
  display: flex;
  justify-content: flex-end;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s;
}
.modal-overlay.open, .modal-overlay.active { opacity: 1; pointer-events: all; }
.modal {
  width: 70vw;
  max-width: 70vw;
  height: 100vh;
  background: var(--black);
  border-left: 1px solid var(--gray-border);
  overflow-y: auto;
  transform: translateX(100%);
  transition: transform 0.4s cubic-bezier(0.16, 1, 0.3, 1);
  position: relative;
}
.modal-overlay.open .modal, .modal-overlay.active .modal { transform: translateX(0); }
.modal-close {
  position: sticky;
  top: 1rem;
  float: right;
  margin: 1rem;
  background: rgba(10,10,10,0.7);
  backdrop-filter: blur(4px);
  border: 1px solid var(--gray-border);
  color: var(--white);
  width: 44px; height: 44px;
  font-size: 1.3rem;
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  z-index: 10;
  transition: all 0.3s;
}
.modal-close:hover { border-color: var(--yellow); color: var(--yellow); }
/* Legacy centered modal (for recording playback etc.) */
.modal-overlay.centered { justify-content: center; align-items: center; }
.modal-overlay.centered .modal { width: 90%; max-width: 800px; height: auto; max-height: 85vh; transform: translateY(20px); border-left: none; border: 1px solid var(--gray-border); }
.modal-overlay.centered.open .modal { transform: translateY(0); }

@media (max-width: 768px) {
  .modal { width: 100%; max-width: 100%; }
}

/* ─── VIDEO PLAYER ─── */
.video-player-container {
  margin-top: 80px;
  padding: 2rem 3rem;
}
.video-player {
  width: 100%;
  aspect-ratio: 16/9;
  background: #000;
  margin-bottom: 2rem;
}
.video-player iframe {
  width: 100%;
  height: 100%;
  border: none;
}
.video-details h1 {
  font-family: var(--serif);
  font-size: 2rem;
  font-weight: 400;
  margin-bottom: 0.5rem;
}
.video-details .meta {
  color: var(--gray);
  font-size: 0.85rem;
  margin-bottom: 1rem;
}
.video-details .description {
  color: var(--gray);
  line-height: 1.7;
  max-width: 700px;
}

/* ─── MARKDOWN CONTENT (writeups, modal, topic pages) ─── */
.modal-writeup h2, .modal-writeup h3, .modal-writeup h4, .concept-writeup h2, .concept-writeup h3, .concept-writeup h4 {
  font-family: var(--serif); font-weight: 400; margin: 1.2rem 0 0.5rem; color: var(--white);
}
.modal-writeup h2, .concept-writeup h2 { font-size: 1.15rem; }
.modal-writeup h3, .concept-writeup h3 { font-size: 1rem; color: var(--yellow); }
.modal-writeup p, .concept-writeup p { margin-bottom: 0.7rem; }
.modal-writeup ul, .modal-writeup ol, .concept-writeup ul, .concept-writeup ol { margin: 0.5rem 0 0.8rem 1.5rem; }
.modal-writeup li, .concept-writeup li { margin-bottom: 0.25rem; }
.modal-writeup code, .concept-writeup code { background: rgba(245,197,24,0.08); padding: 0.1rem 0.35rem; font-size: 0.85em; color: var(--yellow); font-family: 'JetBrains Mono', monospace; }
.modal-writeup pre, .concept-writeup pre { background: rgba(0,0,0,0.3); padding: 1rem; overflow-x: auto; margin: 0.8rem 0; border: 1px solid var(--gray-border); }
.modal-writeup pre code, .concept-writeup pre code { background: none; padding: 0; color: var(--white); }
.modal-writeup blockquote, .concept-writeup blockquote { border-left: 3px solid var(--yellow); padding-left: 1rem; color: var(--gray); margin: 0.8rem 0; font-style: italic; }
.modal-writeup strong, .concept-writeup strong { color: var(--yellow); font-weight: 600; }
.modal-writeup table, .concept-writeup table { width: 100%; border-collapse: collapse; margin: 0.8rem 0; }
.modal-writeup th, .modal-writeup td, .concept-writeup th, .concept-writeup td { padding: 0.45rem 0.7rem; border: 1px solid var(--gray-border); font-size: 0.83rem; }
.modal-writeup th, .concept-writeup th { background: rgba(245,197,24,0.06); color: var(--yellow); font-weight: 600; text-align: left; }

/* ─── FOOTER ─── */
footer {
  padding: 3rem;
  border-top: 1px solid var(--gray-border);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}
footer .copyright {
  font-size: 0.75rem;
  color: var(--gray);
}
footer .footer-links {
  display: flex;
  gap: 1.5rem;
}
footer .footer-links a {
  font-size: 0.75rem;
  color: var(--gray);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  transition: color 0.3s;
}
footer .footer-links a:hover { color: var(--yellow); }

/* ─── ANIMATIONS ─── */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(24px); }
  to { opacity: 1; transform: translateY(0); }
}
@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.4; }
}
@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.7s cubic-bezier(0.16, 1, 0.3, 1), transform 0.7s cubic-bezier(0.16, 1, 0.3, 1);
}
.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ─── LOADING / SPINNER ─── */
.spinner {
  width: 24px; height: 24px;
  border: 2px solid var(--gray-border);
  border-top-color: var(--yellow);
  border-radius: 50%;
  animation: spin 0.6s linear infinite;
}
@keyframes spin {
  to { transform: rotate(360deg); }
}
.loading-overlay {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 4rem;
}

/* ─── EMPTY STATE ─── */
.empty-state {
  text-align: center;
  padding: 4rem 2rem;
  color: var(--gray);
}
.empty-state .icon { font-size: 3rem; margin-bottom: 1rem; }
.empty-state h3 {
  font-family: var(--serif);
  font-size: 1.5rem;
  color: var(--white);
  margin-bottom: 0.5rem;
}

/* ─── SCROLLBAR ─── */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--black); }
::-webkit-scrollbar-thumb { background: var(--gray-border); }
::-webkit-scrollbar-thumb:hover { background: var(--gray); }

/* ─── RESPONSIVE ─── */
@media (max-width: 1024px) {
  .features-grid { grid-template-columns: repeat(2, 1fr); }
  .ai-profiles-grid { grid-template-columns: repeat(2, 1fr); }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .dashboard-grid { grid-template-columns: repeat(2, 1fr); }
  .hero h1 { font-size: clamp(2.5rem, 6vw, 5rem); }
}

/* Switch nav to hamburger earlier so 8 links don't jam the header
   at tablet / half-screen desktop widths (~768-1024px). */
@media (max-width: 1024px) {
  .nav-links { display: none; }
  .nav-mobile-toggle { display: flex; }
}

@media (max-width: 768px) {
  nav { padding: 1rem 1.5rem; }
  nav.scrolled { padding: 0.8rem 1.5rem; }
  .hero { padding: 6rem 1.5rem 4rem; }
  .section { padding: 4rem 1.5rem; }
  .features-grid { grid-template-columns: 1fr; }
  .ai-profiles-grid { grid-template-columns: 1fr; }
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
  .dashboard-grid { grid-template-columns: 1fr; }
  .hero-stats { flex-direction: column; gap: 1.5rem; }
  .hero-actions { flex-direction: column; align-items: flex-start; }
  .tutor-card { flex-direction: column; }
  .admin-sidebar { display: none; }
  .admin-content { padding: 5rem 1.5rem 2rem; }
  .chat-message { max-width: 85%; }
  footer { flex-direction: column; text-align: center; }
  .video-player-container { padding: 1rem 1.5rem; }
}

@media (max-width: 480px) {
  .hero { padding: 5rem 1rem 3rem; }
  .section { padding: 3rem 1rem; }
  .card, .feature-card { padding: 1.5rem; }
  .auth-card { padding: 2rem; }
  .test-meta { flex-wrap: wrap; gap: 1rem; }
}

/* ─── Loading overlay (animated atom-hex logo) ─── */
.di-loader {
  position: fixed; inset: 0;
  background: radial-gradient(circle at 50% 45%, #141410 0%, #0a0a0a 70%);
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  z-index: 9999; gap: 1.6rem;
  animation: di-loader-in 0.25s ease-out;
}
@keyframes di-loader-in { from { opacity: 0; } to { opacity: 1; } }
.di-loader.fade-out { animation: di-loader-out 0.35s ease-in forwards; }
@keyframes di-loader-out { to { opacity: 0; pointer-events: none; } }
.di-loader-logo { width: 92px; height: 92px; filter: drop-shadow(0 0 24px rgba(245,197,24,0.25)); }
.di-loader-text {
  font-family: var(--sans, system-ui);
  font-size: 0.7rem; letter-spacing: 0.28em; text-transform: uppercase;
  color: #666; font-weight: 500;
}
.di-loader-text .gold { color: var(--yellow, #f5c518); animation: di-dots 1.4s infinite; }
@keyframes di-dots { 0%,20%{opacity:0.3} 50%{opacity:1} 100%{opacity:0.3} }

/* Inline spinner (small, for button/section states) */
.di-spinner {
  display: inline-block; width: 20px; height: 20px; vertical-align: middle;
  animation: di-spin 1.2s linear infinite;
}
@keyframes di-spin { to { transform: rotate(360deg); } }

/* ─── Mini inline logo loader (replaces generic spinner) ─── */
.di-mini {
  display: inline-block; vertical-align: middle;
  width: 20px; height: 20px; flex-shrink: 0;
}
.di-mini.lg { width: 32px; height: 32px; }
.di-mini.sm { width: 14px; height: 14px; }

/* ─── Logo alignment safety (brand + tag) ─── */
.nav-logo-text > .nav-logo-brand,
.nav-logo-text > .nav-logo-tag {
  display: block;
  width: 100%;
  text-align: left;
}
.nav-logo-text { min-width: 0; }

/* ─── Multi-format question renderer (shared by /tests + /full-tests) ─── */
.q-body { padding: 1.2rem 0; }
.q-text { font-size: 0.95rem; line-height: 1.75; margin-bottom: 1rem; color: var(--white); }
.q-format-badge {
  display: inline-block; font-size: 0.62rem; letter-spacing: 0.12em;
  text-transform: uppercase; color: var(--yellow);
  border: 1px solid rgba(245,197,24,0.3); padding: 0.2rem 0.6rem;
  margin-bottom: 0.7rem;
}
.q-diagram { margin-bottom: 1rem; background: #0b0b0b; border: 1px solid var(--gray-border); }
.q-diagram img { max-width: 100%; display: block; cursor: zoom-in; transition: transform 0.25s; }
.q-diagram img.zoomed { transform: scale(1.8); transform-origin: top center; cursor: zoom-out; }
.q-diagram-hint { font-size: 0.58rem; color: var(--gray); text-align: center; padding: 0.3rem; letter-spacing: 0.08em; text-transform: uppercase; }

.q-opts { display: flex; flex-direction: column; gap: 0.45rem; }
.q-opt {
  display: flex; align-items: flex-start; gap: 0.7rem;
  padding: 0.7rem 0.9rem; border: 1px solid var(--gray-border);
  cursor: pointer; transition: border-color 0.15s, background 0.15s;
  background: var(--card-bg);
}
.q-opt input { display: none; }
.q-opt-letter {
  flex-shrink: 0; width: 24px; height: 24px; display: inline-flex;
  align-items: center; justify-content: center;
  border: 1px solid var(--gray-border); font-size: 0.7rem; font-weight: 600;
  color: var(--gray); background: transparent;
}
.q-opt-text { font-size: 0.88rem; line-height: 1.55; }
.q-opt:hover { border-color: var(--yellow); }
.q-opt.selected, .q-opt:has(input:checked) { border-color: var(--yellow); background: rgba(245,197,24,0.06); }
.q-opt.selected .q-opt-letter, .q-opt:has(input:checked) .q-opt-letter { border-color: var(--yellow); color: var(--yellow); }

.q-numeric { margin-top: 0.6rem; }
.q-numeric-input {
  width: 100%; max-width: 320px; padding: 0.7rem 0.9rem;
  background: var(--card-bg); border: 1px solid var(--gray-border);
  color: var(--white); font-family: 'JetBrains Mono', monospace; font-size: 0.95rem;
  letter-spacing: 0.05em; transition: border-color 0.15s;
}
.q-numeric-input:focus { outline: none; border-color: var(--yellow); }

.q-match-grid {
  display: grid; grid-template-columns: 1fr 1fr; gap: 0.8rem;
  margin-bottom: 1rem; border: 1px solid var(--gray-border); background: var(--card-bg);
}
.q-match-col { padding: 0.8rem; }
.q-match-col + .q-match-col { border-left: 1px solid var(--gray-border); }
.q-match-head {
  font-size: 0.62rem; letter-spacing: 0.15em; text-transform: uppercase;
  color: var(--yellow); font-weight: 600; margin-bottom: 0.6rem;
  padding-bottom: 0.4rem; border-bottom: 1px solid var(--gray-border);
}
.q-match-row { display: flex; gap: 0.5rem; padding: 0.35rem 0; font-size: 0.85rem; line-height: 1.5; }
.q-match-key { color: var(--yellow); font-weight: 600; flex-shrink: 0; }
.q-match-val { color: var(--white); }

.q-explain {
  margin-top: 0.8rem; padding: 0.8rem 1rem;
  border-left: 3px solid var(--gray-border); background: var(--card-bg);
}
.q-explain.ok { border-left-color: var(--success); }
.q-explain.no { border-left-color: var(--danger); }
.q-explain-head {
  display: flex; align-items: center; gap: 0.5rem;
  font-size: 0.72rem; letter-spacing: 0.1em; text-transform: uppercase;
  font-weight: 700; margin-bottom: 0.4rem;
}
.q-explain.ok .q-explain-head { color: var(--success); }
.q-explain.no .q-explain-head { color: var(--danger); }
.q-explain-mark { font-size: 1rem; }
.q-explain-ans { font-size: 0.85rem; color: var(--white); margin-bottom: 0.4rem; }
.q-explain-body { font-size: 0.8rem; color: var(--gray); line-height: 1.6; }

@media (max-width: 520px) {
  .q-match-grid { grid-template-columns: 1fr; }
  .q-match-col + .q-match-col { border-left: none; border-top: 1px solid var(--gray-border); }
}

/* ─── Comprehension cluster (INPhO-style multi-part problems) ─── */
.q-cluster { padding: 0.4rem 0; }
.q-passage {
  margin: 0 0 1.2rem 0;
  border: 1px solid rgba(245,197,24,0.2);
  background: rgba(245,197,24,0.03);
  padding: 1rem 1.2rem;
  position: sticky; top: 70px; z-index: 5;
}
.q-passage-head {
  font-size: 0.62rem; letter-spacing: 0.15em; text-transform: uppercase;
  font-weight: 700; color: var(--yellow); margin-bottom: 0.5rem;
}
.q-passage-body {
  font-size: 0.88rem; color: var(--white); line-height: 1.75;
}
.q-subpart-head {
  display: flex; align-items: center; gap: 0.6rem;
  padding: 0.5rem 0; border-top: 1px dashed var(--gray-border); margin-top: 0.3rem;
}
.q-subpart-label {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.72rem; color: var(--yellow); font-weight: 600;
  letter-spacing: 0.04em;
}
.q-topic-chip {
  display: inline-block; margin-left: 0.5rem;
  font-size: 0.58rem; letter-spacing: 0.08em; text-transform: uppercase;
  padding: 0.15rem 0.5rem; color: var(--gray); border: 1px solid var(--gray-border);
}

/* ─── PYQ year tag (above question stem in all test runners) ─── */
.q-pyq-tag {
  display: inline-flex; align-items: center; gap: 0.4rem;
  font-size: 0.6rem; letter-spacing: 0.12em; text-transform: uppercase;
  font-weight: 700;
  color: var(--yellow);
  padding: 0.2rem 0.55rem; margin-bottom: 0.55rem;
  background: rgba(245,197,24,0.08);
  border: 1px solid rgba(245,197,24,0.28);
  border-radius: 2px;
}
.q-pyq-dot {
  width: 6px; height: 6px; border-radius: 50%;
  background: var(--yellow);
  box-shadow: 0 0 6px rgba(245,197,24,0.8);
  flex-shrink: 0;
}

/* Test-series tier groupings on /tests */
.ts-tier-group { margin-bottom: 1.6rem; }
.ts-tier-label {
  font-size: 0.7rem; letter-spacing: 0.18em; text-transform: uppercase;
  font-weight: 700; color: var(--yellow);
  margin-bottom: 0.6rem; padding-bottom: 0.3rem;
  border-bottom: 1px solid var(--gray-border);
}
.ts-tier-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 0.8rem;
}

/* Cohort / percentile block on the results screen */
.cohort-block {
  padding: 0.9rem 1.1rem;
  border: 1px solid var(--gray-border);
  background: var(--card-bg);
}
.cohort-row {
  display: flex; justify-content: space-between; align-items: baseline;
  padding: 0.35rem 0;
  font-size: 0.85rem; color: var(--gray);
}
.cohort-row strong {
  color: var(--yellow); font-size: 1.05rem;
  font-variant-numeric: tabular-nums;
}

/* ─── Study focus mode ────────────────────────────────────────────────
   Page-level "give me only the content" toggle, used on topic/concept
   pages. Hides global chrome (nav, mobile menu, footer) and adds an
   exit pill. Combined with the Fullscreen API in main.js for true
   browser-chrome-free reading. */
body.study-focus #nav,
body.study-focus nav,
body.study-focus .mobile-menu,
body.study-focus footer { display: none !important; }
body.study-focus { padding-top: 0 !important; }
body.study-focus .topic-page { padding-top: 1.5rem !important; }
body.study-focus #studyFocusExit {
  position: fixed; top: 0.6rem; right: 0.6rem; z-index: 9999;
  background: rgba(20,20,20,0.7); color: var(--yellow);
  border: 1px solid rgba(245,197,24,0.4); border-radius: 999px;
  padding: 0.3rem 0.7rem; font-size: 0.7rem; letter-spacing: 0.08em;
  cursor: pointer; backdrop-filter: blur(6px);
}
body.study-focus #studyFocusExit:hover { background: rgba(245,197,24,0.15); }
[data-theme="light"] body.study-focus #studyFocusExit {
  background: rgba(255,255,255,0.85); color: #6b4c00;
  border-color: rgba(107,76,0,0.3);
}
/* When focus is engaged from inside the concept modal, expand the modal to
   fill the whole viewport instead of its 70vw side panel. The dim overlay
   collapses too so KaTeX/iframes paint cleanly edge-to-edge. */
body.study-focus .modal-overlay { background: var(--black); backdrop-filter: none; }
body.study-focus .modal-overlay .modal {
  width: 100vw !important; max-width: 100vw !important; border-left: none !important;
}