/* ============================================================
   Mock Test Mitra™ — main.css
   Global stylesheet: layout, components, dark mode, animations
   ============================================================ */

/* ---------- 1. CSS Variables (Light mode defaults) ---------- */
:root {
  /* Brand */
  --primary:        #0d47a1;
  --secondary:      #1565c0;

  /* Nav glow */
  --nav-glow-1:     #00e5ff;
  --nav-glow-2:     #7c4dff;
  --nav-glow-3:     rgba(255,255,255,0.95);

  /* Theme surfaces */
  --bg:             #ffffff;
  --bg-secondary:   #f5f5f5;
  --card-bg:        #f5f7fa;
  --text:           #111111;
  --text-secondary: #444444;
  --border:         #e0e0e0;
  --shadow:         rgba(0,0,0,0.1);

  /* Footer */
  --footer-bg:      #f0f0f0;
  --footer-text:    #333333;
  --footer-link:    #0d47a1;

  /* Radius */
  --radius-sm:  6px;
  --radius-md:  10px;
  --radius-lg:  16px;

  /* Content / Study Material palette */
  --content-primary:   #1a3c6e;
  --content-accent:    #4a90e2;
  --surface-alt:       #f0f4fb;
  --surface-hover:     #dce8ff;
  --surface-stripe:    #f5f8ff;
  --divider-light:     #e0e8f5;

  /* Status colours */
  --clr-success:  #43a047;
  --clr-warning:  #f5a623;
  --clr-danger:   #e53935;
  --clr-info:     #2196f3;

  /* Animation timing scale */
  --dur-fast:    0.15s;
  --dur-normal:  0.25s;
  --dur-slow:    0.35s;

  /* Spacing scale (4-point grid) */
  --sp-1:   4px;
  --sp-2:   8px;
  --sp-3:  12px;
  --sp-4:  16px;
  --sp-5:  20px;
  --sp-6:  24px;
  --sp-8:  32px;
  --sp-10: 40px;
  --sp-12: 48px;
  --sp-16: 64px;
  --sp-20: 80px;

  /* Shadow scale */
  --shadow-sm: 0 1px 4px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.10);
  --shadow-lg: 0 8px 30px rgba(0,0,0,0.15);

  /* Input tokens */
  --input-bg:     #ffffff;
  --input-border: #cdd6e8;
  --input-focus:  #1976d2;

  /* Z-index layers */
  --z-base:    100;
  --z-float:   200;
  --z-overlay: 300;
  --z-sidebar: 400;
  --z-topbar:  500;
  --z-modal:   1000;

  /* Focus ring */
  --focus-ring: 0 0 0 3px rgba(13,71,161,0.25);

  /* Navigation text */
  --nav-text: #5a6a7e;

  /* Content hierarchy */
  --content-h4: #2a5298;

  /* Type scale (mobile-first, scaled via html font-size)
     xs   → badges, captions, tiny meta
     sm   → secondary text, breadcrumbs
     base → body / content text
     md   → standard UI, table text
     lg   → h4, sub-headings
     xl   → h3, section headings
     2xl  → h2, card / page titles
     3xl  → h1, major page headings          */
  --fs-xs:    0.7rem;    /* ~11px  */
  --fs-sm:    0.8rem;    /* ~13px  */
  --fs-base:  0.9rem;    /* ~14.5px */
  --fs-md:    1rem;      /*  16px  */
  --fs-lg:    1.15rem;   /* ~18px  */
  --fs-xl:    1.3rem;    /* ~21px  */
  --fs-2xl:   1.55rem;   /* ~25px  */
  --fs-3xl:   1.9rem;    /*  30px  */
}

/* ---------- 2. Dark Mode ---------- */
[data-theme="dark"] {
  --primary:        #90caf9;
  --secondary:      #64b5f6;

  --nav-glow-1:     #00bcd4;
  --nav-glow-2:     #9575cd;
  --nav-glow-3:     rgba(255,255,255,0.7);

  --bg:             #121212;
  --bg-secondary:   #1e1e1e;
  --card-bg:        #1e1e1e;
  --text:           #e0e0e0;
  --text-secondary: #bbbbbb;
  --border:         #333333;
  --shadow:         rgba(0,0,0,0.5);

  --footer-bg:      #1a1a1a;
  --footer-text:    #aaaaaa;
  --footer-link:    #90caf9;

  /* Content / Study Material palette — dark overrides */
  --content-primary:   #90caf9;
  --content-accent:    #4a90e2;
  --surface-alt:       #1e2a3a;
  --surface-hover:     #162032;
  --surface-stripe:    #1a2233;
  --divider-light:     #2a3a55;

  /* Input overrides */
  --input-bg:     #2a2a2a;
  --input-border: #444444;
  --input-focus:  #64b5f6;

  /* Shadow overrides */
  --shadow-sm: 0 1px 4px rgba(0,0,0,0.25);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.40);
  --shadow-lg: 0 8px 30px rgba(0,0,0,0.50);

  /* Focus ring */
  --focus-ring: 0 0 0 3px rgba(100,181,246,0.25);

  /* Navigation text */
  --nav-text: #7a8fa8;

  /* Content hierarchy */
  --content-h4: var(--secondary);
}

/* ---------- 3. Global Reset & Box Sizing ---------- */
html {
  box-sizing: border-box;
  font-size: 16px;               /* base → 1rem = 16px */
}

/* Slightly smaller base on small phones */
@media (max-width: 480px) {
  html { font-size: 15px; }
}

*, *::before, *::after { box-sizing: inherit; }

/* ---------- 4. Global Transitions ---------- */
*, *::before, *::after {
  transition:
    background-color 0.25s ease,
    color            0.25s ease,
    border-color     0.25s ease;
}

/* ---------- 5. Accessibility ---------- */
.sr-only {
  position: absolute;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

/* Universal focus ring — consistent keyboard nav across all pages */
:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}
button:focus-visible,
a:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
  box-shadow: var(--focus-ring);
}

/* ---------- 6. Body ---------- */
body {
  margin: 0;
  padding: 0;
  font-family: 'Poppins', 'Helvetica Neue', Arial, sans-serif;
  background-color: var(--bg);
  color: var(--text);
  line-height: 1.6;
}

/* ---------- 7. Header ---------- */
header {
  background: linear-gradient(90deg, #0d47a1, #1976d2);
  color: #fff;
  padding: 18px 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  box-shadow: 0 4px 8px rgba(0,0,0,0.15);
  position: sticky;
  top: 0;
  z-index: 100;
}

header h1 {
  margin: 0;
  font-size: var(--fs-2xl);   /* 1.55rem ≈ 25px */
  font-family: 'Playfair Display', serif;
  font-weight: 700;
  letter-spacing: .5px;
  white-space: nowrap;
}

@media (max-width: 480px) {
  header h1 { font-size: var(--fs-xl); }  /* 1.35rem ≈ 21px on small phones */
}

/* Logo */
.logo {
  position: relative;
  color: #fff;
  text-decoration: none;
  display: inline-block;
}
.logo::after {
  content: "";
  position: absolute;
  width: 0; height: 3px;
  left: 0; bottom: -4px;
  background: linear-gradient(90deg, var(--nav-glow-1), var(--nav-glow-2));
  border-radius: 2px;
  transition: width 0.4s ease;
}
.logo:hover::after { width: 100%; }

/* ---------- 8. Navigation ---------- */
nav ul {
  list-style: none;
  margin: 0; padding: 0;
  display: flex;
  gap: 28px;
  align-items: center;
}

nav ul li a {
  text-decoration: none;
  color: #fff;
  font-size: var(--fs-md);  /* 1rem — stable rem, was 1.05em */
  font-weight: 600;
  position: relative;
  transition: color 0.3s ease, transform 0.3s ease;
}
nav ul li a::after {
  content: "";
  position: absolute;
  width: 0; height: 3px;
  left: 0; bottom: -4px;
  background: linear-gradient(90deg, var(--nav-glow-1), var(--nav-glow-2));
  border-radius: 2px;
  transition: width 0.4s ease;
}
nav ul li a:hover {
  color: #fff;
  transform: scale(1.07);
  text-shadow: 0 0 6px var(--nav-glow-3), 0 0 16px var(--nav-glow-1), 0 0 28px var(--nav-glow-2);
  filter: drop-shadow(0 0 4px var(--nav-glow-1));
}
nav ul li a:hover::after { width: 100%; }
nav ul li a:focus-visible {
  outline: none;
  color: #fff;
  text-shadow: 0 0 6px var(--nav-glow-1), 0 0 16px var(--nav-glow-2);
}

/* Theme toggle button */
.theme-toggle {
  background: transparent;
  border: 1.5px solid rgba(255,255,255,0.5);
  border-radius: 20px;
  cursor: pointer;
  font-size: 1rem;
  padding: 4px 10px;
  line-height: 1;
  color: #fff;
  vertical-align: middle;
}
.theme-toggle:hover {
  background: rgba(255,255,255,0.15);
  border-color: rgba(255,255,255,0.85);
}

/* ---------- 9. Layout Container ---------- */
.container {
  padding: 32px 20px 80px;
  max-width: 1280px;
  margin: 0 auto;
  background-color: var(--bg);
}

/* ---------- 10. Glass Card ---------- */
.card {
  background: var(--card-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  padding: 20px 16px;
  margin-bottom: 30px;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  border: 1px solid rgba(255,255,255,0.4);
  position: relative;
  overflow: hidden;
  opacity: 0;
  transform: translateY(20px) scale(.98);
  animation: fadeUp .8s cubic-bezier(.2,.6,.3,1) forwards;
  animation-delay: .15s;
  color: var(--text);
}
.card::before {
  content: "";
  position: absolute;
  top: -100%; left: -100%;
  width: 200%; height: 200%;
  background: radial-gradient(circle at 30% 30%, rgba(255,255,255,0.25), transparent 60%);
  opacity: 0;
  transition: opacity 0.5s ease;
  pointer-events: none;
}
.card:hover::before { opacity: 1; }
.card:hover {
  transform: translateY(-5px) scale(1.01);
  box-shadow: 0 8px 30px rgba(0,0,0,0.15), 0 0 20px rgba(255,255,255,0.4);
  border: 1px solid rgba(41,11,159,0.6);
}

.card h2 {
  margin-top: 0;
  font-size: var(--fs-2xl);    /* 1.65rem ≈ 26px */
  color: var(--primary);
  font-family: 'Playfair Display', serif;
}
.card h3 { font-size: var(--fs-xl); }    /* 1.35rem ≈ 22px */
.card ol { font-size: var(--fs-md); margin: 1em 0 0 1.2em; padding: 0; }
.card ol li { font-size: var(--fs-md); margin-bottom: 0.5em; }
.card ol li a { font-size: var(--fs-md); text-decoration: none; transition: color 0.2s, text-shadow 0.2s; }
.card ol li a:hover,
.card ol li a:focus-visible {
  color: #1976d2;
  text-shadow: 0 2px 8px rgba(25,118,210,0.18);
  outline: none;
}

/* ---------- 11. Subjects Grid ---------- */
.subjects {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 28px;
  margin-top: 20px;
}

/* ---------- 11b. Filter Chips ---------- */
.filter-chips {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  scrollbar-width: none;
  -ms-overflow-style: none;
  padding: 4px 0 8px;
  margin-top: 16px;
}
.filter-chips::-webkit-scrollbar { display: none; }

.filter-chip {
  flex-shrink: 0;
  padding: 6px 16px;
  border-radius: 999px;
  border: 1.5px solid var(--border);
  background: var(--bg);
  color: var(--text-secondary);
  font-size: var(--fs-sm);
  font-weight: 600;
  cursor: pointer;
  font-family: inherit;
  transition: background 0.15s, color 0.15s, border-color 0.15s;
  white-space: nowrap;
}
.filter-chip:hover {
  border-color: var(--primary);
  color: var(--primary);
}
.filter-chip.active {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}
[data-theme="dark"] .filter-chip {
  background: var(--card-bg);
  border-color: #444;
  color: #aaa;
}
[data-theme="dark"] .filter-chip.active {
  background: var(--secondary);
  border-color: var(--secondary);
  color: #fff;
}

.subject-card {
  --accent1:    #ff8a00;
  --accent2:    #e52e71;
  --badge-bg:   #d35400;
  --badge-text: #fff;

  display: block;
  text-decoration: none;
  color: inherit;
  position: relative;
  padding: 56px 25px 52px;
  text-align: center;
  border-radius: var(--radius-lg);
  background: rgba(255,255,255,0.65);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid rgba(255,255,255,0.35);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
  opacity: 0;
  transform: translateY(20px) scale(.98);
  animation: fadeUp .7s cubic-bezier(.2,.6,.3,1) forwards;
  animation-delay: var(--delay, 0s);
}
.subject-card::after {
  content: "";
  position: absolute;
  left: 50%; bottom: 18px;
  width: 0; height: 3px;
  transform: translateX(-50%);
  background: linear-gradient(90deg, var(--accent1), var(--accent2));
  border-radius: 2px;
  transition: width 0.45s ease;
}
.subject-card:hover {
  transform: translateY(-6px) scale(1.03);
  box-shadow: var(--shadow-lg), 0 0 22px var(--accent1), 0 0 44px var(--accent2);
  border: 1px solid var(--accent1);
  color: #0d47a1;
}
.subject-card:hover::after { width: 60%; }
.subject-card:focus-visible {
  outline: none;
  transform: translateY(-6px) scale(1.03);
  box-shadow: 0 0 0 3px var(--accent2), 0 0 18px var(--accent1);
  border: 1px solid var(--accent2);
}

/* Dark mode subject cards */
[data-theme="dark"] .subject-card {
  background: rgba(30,30,30,0.85) !important;
  border-color: #333 !important;
}
[data-theme="dark"] .subject-card:hover { color: var(--primary); }

/* Subject card internals */
.subject-title {
  display: block;
  font-size: 1.25em;
  font-weight: 600;
  color: var(--primary);
}
.subject-card:hover .subject-title {
  color: #000;
  text-shadow: 0 0 4px #fff, 0 0 12px var(--accent1), 0 0 24px var(--accent2);
}
[data-theme="dark"] .subject-title { color: var(--text); }

.subject-sub {
  display: block;
  font-size: var(--fs-xs);
  font-weight: 500;
  color: var(--text-secondary);
  margin-top: 6px;
  letter-spacing: 0.3px;
}
[data-theme="dark"] .subject-sub { color: #888; }

/* Social proof chip on active exam cards */
.activity-chip {
  display: block;
  margin-top: 8px;
  padding: 3px 10px;
  background: rgba(46, 125, 50, 0.10);
  color: #2e7d32;
  border: 1px solid rgba(46, 125, 50, 0.25);
  border-radius: 999px;
  font-size: var(--fs-xs);
  font-weight: 600;
  letter-spacing: 0.02em;
}
[data-theme="dark"] .activity-chip {
  background: rgba(76, 175, 80, 0.12);
  color: #81c784;
  border-color: rgba(76, 175, 80, 0.25);
}

.subject-icon {
  display: inline-block;
  margin-bottom: 16px;
  width: 48px; height: 48px;
}
.subject-icon svg {
  width: 48px; height: 48px;
  stroke: var(--accent1);
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
  fill: none;
  transition: stroke 0.35s ease, transform 0.35s ease, filter 0.35s ease;
}
.subject-card:hover .subject-icon svg {
  stroke: var(--accent2);
  filter: drop-shadow(0 0 4px var(--accent1)) drop-shadow(0 0 10px var(--accent2));
  transform: scale(1.08);
}

/* Badges */
.badge, .corner-label {
  position: absolute;
  padding: 2px 10px 3px;
  font-size: .75rem;
  font-weight: 700;
  border-radius: 999px;
  line-height: 1.2;
  pointer-events: none;
  text-transform: uppercase;
  letter-spacing: .5px;
}
.badge {
  top: 12px; right: 12px;
  background: var(--badge-bg);
  color: var(--badge-text);
}
.badge.soon {
  background: repeating-linear-gradient(
    -45deg,
    var(--badge-bg), var(--badge-bg) 6px,
    rgba(255,255,255,.35) 6px, rgba(255,255,255,.35) 12px
  );
  color: #000;
}
.corner-label {
  top: 12px; left: 12px;
  background: var(--badge-bg);
  color: #000;
}

/* ---------- 11b. Exam Section Headers ---------- */
.exam-section-header {
  grid-column: 1 / -1;
  display: flex;
  align-items: center;
  gap: 16px;
  margin: 24px 0 4px;
}
.exam-section-header:first-child { margin-top: 4px; }
.exam-section-header span {
  font-size: .7rem;
  font-weight: 700;
  letter-spacing: 1.4px;
  text-transform: uppercase;
  color: var(--text-secondary);
  white-space: nowrap;
  padding: 3px 12px;
  border-radius: 999px;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
}
.exam-section-header::before,
.exam-section-header::after {
  content: "";
  flex: 1;
  height: 1px;
  background: var(--border);
}
[data-theme="dark"] .exam-section-header span {
  background: rgba(255,255,255,0.07);
  border-color: #444;
  color: #aaa;
}

/* ---------- 12. Footer ---------- */
footer {
  text-align: center;
  padding: 15px 0;
  background-color: var(--footer-bg);
  color: var(--footer-text);
}
footer a { color: var(--footer-link); }

/* ---------- 13. Utility Buttons ---------- */
.exam-btn {
  display: inline-block;
  padding: var(--sp-2) var(--sp-3);
  background: var(--primary);
  color: #fff;
  text-decoration: none;
  border-radius: var(--radius-sm);
  font-size: var(--fs-sm);
  font-weight: 600;
  transition: opacity var(--dur-fast) ease;
}
.exam-btn:hover { opacity: 0.85; }

/* ---------- 14. Accordion Topics (Study Material pages) ---------- */
.topic {
  cursor: pointer;
  padding: 16px 20px;
  margin-top: 12px;
  border-radius: var(--radius-md);
  background: var(--surface-alt);
  border-left: 5px solid var(--content-accent);
  font-size: var(--fs-md);           /* explicit — was inherited */
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-weight: 600;
  color: var(--content-primary);
  user-select: none;
  transition: background var(--dur-normal) ease;
}
.topic:hover { background: var(--surface-hover); }
.topic.open  { background: var(--surface-hover); border-left-color: var(--content-primary); }
.topic .arrow { transition: transform var(--dur-slow); font-size: 0.85rem; color: var(--content-accent); }
.topic.open .arrow { transform: rotate(90deg); }

.content {
  display: none;
  padding: 22px 26px;
  background: var(--bg);
  border-left: 5px solid var(--content-accent);
  border-radius: 0 0 var(--radius-md) var(--radius-md);
  box-shadow: 0 4px 12px rgba(0,0,0,0.06);
}
.content h3 {
  color: var(--content-primary);
  margin: 18px 0 6px;
  font-size: var(--fs-lg);           /* 1.15rem — was 0.97rem (barely above body) */
  font-weight: 700;
  border-bottom: 1px solid var(--divider-light);
  padding-bottom: 4px;
  letter-spacing: 0.01em;
}
.content h3:first-child { margin-top: 0; }
.content h4 {
  color: var(--content-h4);
  margin: 12px 0 4px;
  font-size: var(--fs-md);           /* 1rem — was 0.93rem (smaller than body!) */
  font-weight: 600;
  letter-spacing: 0.01em;
}
.content ul,
.content ol { margin: 6px 0 12px; padding-left: 22px; line-height: 1.7; }
.content li { margin-bottom: 3px; }
.content p  { line-height: 1.7; color: var(--text-secondary); margin: 8px 0; }

/* ---------- 15. Tables ---------- */
table { width: 100%; border-collapse: collapse; margin: 12px 0 16px; font-size: var(--fs-base); }
th { background: var(--content-primary); color: #fff; padding: 9px 12px; text-align: left; font-weight: 600; font-size: var(--fs-sm); }
td { padding: 8px 12px; border-bottom: 1px solid var(--divider-light); vertical-align: top; }
tr:nth-child(even) td { background: var(--surface-stripe); }
td strong { color: var(--content-primary); }

/* ---------- 16. Info Boxes ---------- */
.note-box    { background: #fffbe6; border-left: 4px solid var(--clr-warning); }
.info-box    { background: #e8f4fd; border-left: 4px solid var(--clr-info); }
.danger-box  { background: #fff0f0; border-left: 4px solid var(--clr-danger); }
.success-box { background: #f0fff4; border-left: 4px solid var(--clr-success); }

.note-box, .info-box, .danger-box, .success-box {
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  margin: 12px 0;
  font-size: var(--fs-base);   /* 0.9rem */
  line-height: 1.7;
}

/* ---------- 17. Formula & Exam Badges ---------- */
.formula {
  background: var(--surface-alt);
  border: 1px solid var(--divider-light);
  border-radius: var(--radius-sm);
  padding: 10px 16px;
  font-family: 'Courier New', monospace;
  font-size: 0.88rem;
  margin: 8px 0;
  color: var(--content-primary);
  line-height: 1.7;
}

.exam-badge {
  display: inline-block;
  border-radius: 4px;
  padding: 2px 9px;
  font-size: var(--fs-xs);   /* 0.7rem */
  font-weight: 700;
  margin: 2px;
  letter-spacing: 0.02em;
  background: #e8f0fe;
  color: var(--content-primary);
}
.exam-badge.gate  { background: #fff3e0; color: #e65100; }
.exam-badge.ese   { background: #e8f5e9; color: #1b5e20; }
.exam-badge.sscje { background: #f3e5f5; color: #4a148c; }
/* Current-affairs variants */
.exam-badge.upsc  { background: #fff3e0; color: #e65100; }
.exam-badge.ssc   { background: #e8f5e9; color: #1b5e20; }
.exam-badge.bank  { background: #f3e5f5; color: #4a148c; }
.exam-badge.rrb   { background: #fce4ec; color: #880e4f; }

/* ---------- 18. Chapter Number Bubble & Chips ---------- */
.ch-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: var(--content-accent);
  color: #fff;
  border-radius: 50%;
  width: 26px; height: 26px;
  font-size: 0.78rem;
  font-weight: 700;
  margin-right: 10px;
  flex-shrink: 0;
}
.topic.open .ch-num { background: var(--content-primary); }

.chapter-list-intro { display: flex; flex-wrap: wrap; gap: 8px; margin: 14px 0 4px; }
.ch-chip {
  background: #e8f0fe;
  color: var(--content-primary);
  border-radius: 20px;
  padding: 4px 14px;
  font-size: var(--fs-sm);   /* 0.8rem */
  font-weight: 600;
  cursor: pointer;
  border: 1px solid var(--divider-light);
  transition: background var(--dur-normal) ease;
}
.ch-chip:hover { background: var(--content-accent); color: #fff; border-color: var(--content-accent); }

/* ---------- 18b. Sleek Intro Card ---------- */
.intro-card {
  padding: 12px 16px 14px;
  margin-bottom: 18px;
}
.intro-card:hover {
  transform: translateY(-2px) scale(1.005);
}
.intro-top {
  display: flex;
  align-items: flex-start;
  flex-wrap: wrap;
  gap: 6px 14px;
}
.intro-top h1, .intro-top h2 {
  font-size: 1.15rem !important;
  margin: 0 !important;
  line-height: 1.35;
  flex: 1 1 180px;
  color: #0d47a1;
}
.intro-badges {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  align-items: center;
  flex-shrink: 0;
}
.intro-desc {
  font-size: var(--fs-sm);   /* 0.8rem */
  line-height: 1.5;
  margin: 6px 0 0 !important;
  opacity: 0.75;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.intro-card .chapter-list-intro {
  flex-wrap: nowrap;
  overflow-x: auto;
  scrollbar-width: none;
  -ms-overflow-style: none;
  gap: 6px;
  margin: 8px 0 0 !important;
  padding-bottom: 2px;
}
.intro-card .chapter-list-intro::-webkit-scrollbar { display: none; }
.intro-card .ch-chip {
  white-space: nowrap;
  font-size: var(--fs-xs);   /* 0.7rem */
  padding: 3px 11px;
}
[data-theme="dark"] .intro-top h1,
[data-theme="dark"] .intro-top h2 { color: var(--secondary); }

/* ---------- 19. Breadcrumb ---------- */
.breadcrumb { font-size: var(--fs-sm); margin-bottom: 14px; color: #666; }
.breadcrumb a { color: var(--content-accent); text-decoration: none; }
.breadcrumb a:hover { text-decoration: underline; }

/* ---------- 20. Diagrams ---------- */
.diagram-wrap {
  background: #f7faff;
  border: 1px solid #d0e2ff;
  border-radius: var(--radius-md);
  padding: 14px 10px 10px;
  margin: 16px 0;
  text-align: center;
}
.diagram-wrap svg { max-width: 100%; height: auto; display: block; margin: 0 auto; }
.diagram-caption {
  font-size: var(--fs-sm);   /* 0.8rem */
  color: #4a6fa5;
  margin-top: 7px;
  font-style: italic;
  font-weight: 600;
  letter-spacing: 0.02em;
}
.diagram-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin: 16px 0;
}

/* ---------- 20b. Dark Mode: Content Components ---------- */
[data-theme="dark"] .topic { background: var(--surface-alt); color: var(--content-primary); border-left-color: var(--content-accent); }
[data-theme="dark"] .topic:hover,
[data-theme="dark"] .topic.open { background: var(--surface-hover); border-left-color: var(--content-primary); }
[data-theme="dark"] .topic .arrow { color: var(--content-primary); }
[data-theme="dark"] .ch-num { background: var(--content-accent); }
[data-theme="dark"] .topic.open .ch-num { background: var(--content-primary); color: #121212; }
[data-theme="dark"] .content { background: #1a1a2e; border-left-color: var(--content-accent); box-shadow: 0 4px 12px rgba(0,0,0,0.3); }
[data-theme="dark"] .content h3 { color: var(--content-primary); border-bottom-color: var(--divider-light); }
[data-theme="dark"] .content h4 { color: var(--content-h4); }
[data-theme="dark"] .content p,
[data-theme="dark"] .content li,
[data-theme="dark"] .content ul,
[data-theme="dark"] .content ol { color: #cccccc; }
[data-theme="dark"] th { background: #0d2137; color: var(--text); }
[data-theme="dark"] td { color: #cccccc; border-bottom-color: var(--divider-light); }
[data-theme="dark"] tr:nth-child(even) td { background: var(--surface-stripe); }
[data-theme="dark"] td strong { color: var(--content-primary); }
[data-theme="dark"] .note-box    { background: #2a2200; border-left-color: var(--clr-warning); color: #e0c97a; }
[data-theme="dark"] .info-box    { background: #0d1f33; border-left-color: var(--clr-info);    color: var(--content-primary); }
[data-theme="dark"] .danger-box  { background: #2a0d0d; border-left-color: var(--clr-danger);  color: #ef9a9a; }
[data-theme="dark"] .success-box { background: #0d2a13; border-left-color: var(--clr-success); color: #a5d6a7; }
[data-theme="dark"] .formula { background: #0d1a2e; border-color: var(--divider-light); color: var(--content-primary); }
[data-theme="dark"] .exam-badge        { background: #1a2a44; color: var(--content-primary); }
[data-theme="dark"] .exam-badge.gate,
[data-theme="dark"] .exam-badge.upsc   { background: #2a1800; color: #ffcc80; }
[data-theme="dark"] .exam-badge.ese,
[data-theme="dark"] .exam-badge.ssc    { background: #0d2a13; color: #a5d6a7; }
[data-theme="dark"] .exam-badge.sscje,
[data-theme="dark"] .exam-badge.bank   { background: #1e0a2a; color: #ce93d8; }
[data-theme="dark"] .exam-badge.rrb    { background: #2a0d1a; color: #f48fb1; }
[data-theme="dark"] .ch-chip { background: #1a2a44; color: var(--content-primary); border-color: var(--divider-light); }
[data-theme="dark"] .ch-chip:hover { background: var(--content-accent); color: #fff; }
[data-theme="dark"] .breadcrumb { color: #aaaaaa; }
[data-theme="dark"] .breadcrumb a { color: var(--secondary); }
[data-theme="dark"] .breadcrumb span { color: #aaaaaa; }
[data-theme="dark"] .diagram-wrap { background: #111827; border-color: var(--divider-light); }
[data-theme="dark"] .diagram-caption { color: var(--content-primary); }

/* ---------- 21. Mock Test / Question Paper ---------- */
.question {
  background: #f1f1f1;
  padding: 25px;
  margin-bottom: 20px;
  border-radius: 8px;
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}
.question h3 { margin-bottom: 10px; }
.options label { display: block; margin-bottom: 5px; }

.submit-btn, .reset-btn {
  margin-top: 10px;
  padding: 8px 14px;
  border: none;
  border-radius: 4px;
  cursor: pointer;
}
.submit-btn { background: #007bff; color: #fff; }
.submit-btn:hover { background: #0056b3; }
.reset-btn { background: #ffc107; color: #000; margin-left: 10px; }

.reveal {
  display: none;
  margin-top: 10px;
  padding: 10px;
  border-left: 4px solid;
  border-radius: 4px;
}
.correct     { background: #d4edda; color: #155724; border-color: #28a745; }
.incorrect   { background: #f8d7da; color: #721c24; border-color: #dc3545; }
.not-attempted { background: #fff3cd; color: #856404; border-color: #ffc107; }
.explanation { margin-top: 5px; font-style: italic; color: #555; }

.score-box {
  margin-top: 30px;
  padding: 15px;
  background: #e7f3fe;
  border-left: 4px solid #2196F3;
  font-weight: bold;
}

.global-buttons { margin-top: 20px; }
.global-buttons button {
  padding: 10px 20px;
  margin-right: 10px;
  font-size: 16px;
  cursor: pointer;
  border-radius: 5px;
  border: none;
}
.submit-all-btn { background: #28a745; color: #fff; }
.reset-all-btn  { background: #6c757d; color: #fff; }
.save-btn       { background: #007bff; color: #fff; }

/* ---------- 22. Animations ---------- */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(20px) scale(.98); }
  to   { opacity: 1; transform: translateY(0)    scale(1);   }
}

/* ---------- 23. Responsive ---------- */
@media (max-width: 600px) {
  header {
    flex-direction: column;
    gap: 10px;
    text-align: center;
  }
  nav ul { gap: 15px; flex-wrap: wrap; justify-content: center; }

  /* Bento 2-column grid */
  .subjects {
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
  }
  .subject-card {
    padding: 38px 10px 26px;
    text-align: center;
  }
  .subject-icon,
  .subject-icon svg {
    width: 32px;
    height: 32px;
    margin-bottom: 8px;
  }
  .subject-title { font-size: 0.82rem; line-height: 1.25; }
  .subject-sub   { display: none; }
  .corner-label  { display: none; }
  .badge { font-size: 0.58rem; padding: 1px 5px 2px; }
  /* De-emphasize coming-soon cards */
  .subject-card:has(.badge.soon) {
    opacity: 0.5;
    pointer-events: none;
  }
  .subject-card:has(.badge.soon):hover {
    transform: none;
    box-shadow: var(--shadow-sm);
  }
  .diagram-row { grid-template-columns: 1fr; }

  /* ── Content area: tighter padding, no horizontal bleed ── */
  .content {
    padding: 14px 10px;
    overflow-x: auto;               /* last-resort scroll for truly unbreakable content */
    -webkit-overflow-scrolling: touch;
  }

  /* ── Mobile table fix ── */
  table {
    font-size: 0.72rem;
    table-layout: fixed;            /* equal column widths, prevents overflow */
    width: 100%;
    word-break: break-word;
    overflow-wrap: break-word;
  }
  th {
    padding: 6px 6px;
    font-size: 0.69rem;
    word-break: break-word;
    overflow-wrap: break-word;
    hyphens: auto;
  }
  td {
    padding: 5px 6px;
    font-size: 0.72rem;
    word-break: break-word;
    overflow-wrap: break-word;
    hyphens: auto;
  }
}