/* ============================================================
   AP VAULT — Design Tokens + Component Styles
   Palette: Deep navy + electric indigo + warm white
   Target: High school students, clean, confident, focused
   ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=DM+Sans:wght@400;500;600;700&family=DM+Mono:wght@400;500&display=swap');

/* ---------- TYPE SCALE ---------- */
:root {
  --text-xs:   clamp(0.75rem,  0.7rem  + 0.25vw, 0.875rem);
  --text-sm:   clamp(0.875rem, 0.8rem  + 0.35vw, 1rem);
  --text-base: clamp(1rem,     0.95rem + 0.25vw, 1.125rem);
  --text-lg:   clamp(1.125rem, 1rem    + 0.75vw, 1.5rem);
  --text-xl:   clamp(1.5rem,   1.2rem  + 1.25vw, 2.25rem);
  --text-2xl:  clamp(2rem,     1.2rem  + 2.5vw,  3.5rem);
  --text-3xl:  clamp(2.5rem,   1rem    + 4vw,    5rem);

  --font-display: 'DM Sans', 'Helvetica Neue', sans-serif;
  --font-body: 'DM Sans', 'Helvetica Neue', sans-serif;
  --font-mono: 'DM Mono', 'Consolas', monospace;

  /* ---------- SPACING ---------- */
  --space-1:  0.25rem;
  --space-2:  0.5rem;
  --space-3:  0.75rem;
  --space-4:  1rem;
  --space-5:  1.25rem;
  --space-6:  1.5rem;
  --space-8:  2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;

  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-full: 9999px;

  --transition-interactive: 180ms cubic-bezier(0.16, 1, 0.3, 1);

  --content-narrow: 640px;
  --content-default: 960px;
  --content-wide: 1200px;
}

/* ---------- LIGHT MODE — Navy/Indigo academic palette ---------- */
:root, [data-theme="light"] {
  --color-bg:              #f8f9fc;
  --color-surface:         #ffffff;
  --color-surface-2:       #f0f2f8;
  --color-surface-offset:  #e8ebf4;
  --color-divider:         #dde1ed;
  --color-border:          #cdd2e4;

  --color-text:            #0f1524;
  --color-text-muted:      #505878;
  --color-text-faint:      #9aa0bc;
  --color-text-inverse:    #f8f9fc;

  --color-primary:         #4338ca;
  --color-primary-hover:   #3730a3;
  --color-primary-active:  #312e81;
  --color-primary-highlight: #e0e7ff;

  --color-ap:              #0ea5e9;
  --color-ap-hover:        #0284c7;
  --color-ap-highlight:    #e0f2fe;

  --color-sat:             #10b981;
  --color-sat-hover:       #059669;
  --color-sat-highlight:   #d1fae5;

  --color-correct:         #16a34a;
  --color-correct-bg:      #dcfce7;
  --color-wrong:           #dc2626;
  --color-wrong-bg:        #fee2e2;
  --color-neutral-bg:      #f1f5f9;

  --shadow-sm: 0 1px 2px rgba(15,21,36,0.06);
  --shadow-md: 0 4px 12px rgba(15,21,36,0.08);
  --shadow-lg: 0 12px 32px rgba(15,21,36,0.12);
}

/* ---------- DARK MODE ---------- */
[data-theme="dark"],
@media (prefers-color-scheme: dark) { :root:not([data-theme]) {
  --color-bg:              #0b0e1a;
  --color-surface:         #111422;
  --color-surface-2:       #161929;
  --color-surface-offset:  #1c2035;
  --color-divider:         #242840;
  --color-border:          #2d3150;

  --color-text:            #e2e6f3;
  --color-text-muted:      #8b92b5;
  --color-text-faint:      #4a5070;
  --color-text-inverse:    #0b0e1a;

  --color-primary:         #818cf8;
  --color-primary-hover:   #a5b4fc;
  --color-primary-active:  #c7d2fe;
  --color-primary-highlight: #1e2040;

  --color-ap:              #38bdf8;
  --color-ap-hover:        #7dd3fc;
  --color-ap-highlight:    #0c2540;

  --color-sat:             #34d399;
  --color-sat-hover:       #6ee7b7;
  --color-sat-highlight:   #052e20;

  --color-correct:         #22c55e;
  --color-correct-bg:      #052e16;
  --color-wrong:           #f87171;
  --color-wrong-bg:        #2d0e0e;
  --color-neutral-bg:      #1c2035;

  --shadow-sm: 0 1px 2px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.4);
  --shadow-lg: 0 12px 32px rgba(0,0,0,0.5);
}}

[data-theme="dark"] {
  --color-bg:              #0b0e1a;
  --color-surface:         #111422;
  --color-surface-2:       #161929;
  --color-surface-offset:  #1c2035;
  --color-divider:         #242840;
  --color-border:          #2d3150;
  --color-text:            #e2e6f3;
  --color-text-muted:      #8b92b5;
  --color-text-faint:      #4a5070;
  --color-text-inverse:    #0b0e1a;
  --color-primary:         #818cf8;
  --color-primary-hover:   #a5b4fc;
  --color-primary-active:  #c7d2fe;
  --color-primary-highlight: #1e2040;
  --color-ap:              #38bdf8;
  --color-ap-hover:        #7dd3fc;
  --color-ap-highlight:    #0c2540;
  --color-sat:             #34d399;
  --color-sat-hover:       #6ee7b7;
  --color-sat-highlight:   #052e20;
  --color-correct:         #22c55e;
  --color-correct-bg:      #052e16;
  --color-wrong:           #f87171;
  --color-wrong-bg:        #2d0e0e;
  --color-neutral-bg:      #1c2035;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.4);
  --shadow-lg: 0 12px 32px rgba(0,0,0,0.5);
}

/* ============================================================
   LAYOUT & NAVIGATION
   ============================================================ */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
}

.header-inner {
  max-width: var(--content-wide);
  margin: 0 auto;
  padding: var(--space-3) var(--space-6);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
}

.logo {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  text-decoration: none;
  color: var(--color-text);
}

.logo-mark {
  flex-shrink: 0;
}

.logo-text {
  font-size: var(--text-base);
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--color-text);
}

.logo-text span {
  color: var(--color-primary);
}

.header-nav {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.nav-tab {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-full);
  font-size: var(--text-sm);
  font-weight: 600;
  text-decoration: none;
  color: var(--color-text-muted);
  border: 1.5px solid transparent;
  cursor: pointer;
}

.nav-tab:hover {
  background: var(--color-surface-2);
  color: var(--color-text);
}

.nav-tab.active-ap {
  background: var(--color-ap-highlight);
  color: var(--color-ap);
  border-color: var(--color-ap);
}

.nav-tab.active-sat {
  background: var(--color-sat-highlight);
  color: var(--color-sat);
  border-color: var(--color-sat);
}

.theme-toggle {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-full);
  color: var(--color-text-muted);
  border: 1px solid var(--color-border);
  flex-shrink: 0;
}

.theme-toggle:hover {
  background: var(--color-surface-2);
  color: var(--color-text);
}

/* ============================================================
   HERO
   ============================================================ */

.hero {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  padding: clamp(var(--space-12), 6vw, var(--space-24)) var(--space-6);
  text-align: center;
}

.hero-inner {
  max-width: var(--content-narrow);
  margin: 0 auto;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  background: var(--color-primary-highlight);
  color: var(--color-primary);
  font-size: var(--text-xs);
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: var(--space-1) var(--space-3);
  border-radius: var(--radius-full);
  margin-bottom: var(--space-5);
}

.hero h1 {
  font-size: var(--text-2xl);
  font-weight: 800;
  letter-spacing: -0.03em;
  color: var(--color-text);
  margin-bottom: var(--space-4);
  line-height: 1.1;
}

.hero p {
  font-size: var(--text-base);
  color: var(--color-text-muted);
  max-width: 52ch;
  margin: 0 auto var(--space-8);
}

.hero-ctas {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
  justify-content: center;
}

/* ============================================================
   BUTTONS
   ============================================================ */

.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-6);
  border-radius: var(--radius-full);
  font-size: var(--text-sm);
  font-weight: 700;
  text-decoration: none;
  cursor: pointer;
  border: none;
  white-space: nowrap;
}

.btn-primary {
  background: var(--color-primary);
  color: #fff;
}
.btn-primary:hover { background: var(--color-primary-hover); }

.btn-ap {
  background: var(--color-ap);
  color: #fff;
}
.btn-ap:hover { background: var(--color-ap-hover); }

.btn-sat {
  background: var(--color-sat);
  color: #fff;
}
.btn-sat:hover { background: var(--color-sat-hover); }

.btn-outline {
  background: transparent;
  color: var(--color-text-muted);
  border: 1.5px solid var(--color-border);
}
.btn-outline:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

/* ============================================================
   SUBJECT SELECTOR TABS
   ============================================================ */

.subject-bar {
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-4) var(--space-6);
  overflow-x: auto;
  scrollbar-width: none;
}

.subject-bar::-webkit-scrollbar { display: none; }

.subject-inner {
  max-width: var(--content-wide);
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.subject-label {
  font-size: var(--text-xs);
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-text-faint);
  white-space: nowrap;
  flex-shrink: 0;
}

.subject-tabs {
  display: flex;
  gap: var(--space-2);
  flex-wrap: nowrap;
}

.subject-tab {
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-full);
  font-size: var(--text-sm);
  font-weight: 600;
  cursor: pointer;
  white-space: nowrap;
  border: 1.5px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text-muted);
  text-decoration: none;
}

.subject-tab:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.subject-tab.active {
  background: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
}

/* ============================================================
   QUIZ AREA
   ============================================================ */

.quiz-container {
  max-width: var(--content-default);
  margin: 0 auto;
  padding: var(--space-8) var(--space-6);
}

.quiz-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-6);
  flex-wrap: wrap;
  gap: var(--space-3);
}

.quiz-meta {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.quiz-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-1) var(--space-3);
  border-radius: var(--radius-full);
  font-size: var(--text-xs);
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.badge-ap {
  background: var(--color-ap-highlight);
  color: var(--color-ap);
}

.badge-sat {
  background: var(--color-sat-highlight);
  color: var(--color-sat);
}

.quiz-progress-wrap {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.quiz-counter {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

.progress-bar-track {
  width: 120px;
  height: 6px;
  background: var(--color-border);
  border-radius: var(--radius-full);
  overflow: hidden;
}

.progress-bar-fill {
  height: 100%;
  background: var(--color-primary);
  border-radius: var(--radius-full);
  transition: width 400ms cubic-bezier(0.16,1,0.3,1);
}

.score-display {
  font-size: var(--text-sm);
  font-weight: 700;
  color: var(--color-correct);
  font-variant-numeric: tabular-nums;
}

/* ============================================================
   QUESTION CARD
   ============================================================ */

.question-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-8);
  box-shadow: var(--shadow-md);
  margin-bottom: var(--space-6);
}

.question-topic {
  font-size: var(--text-xs);
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-text-faint);
  margin-bottom: var(--space-4);
}

.question-text {
  font-size: var(--text-lg);
  font-weight: 600;
  color: var(--color-text);
  line-height: 1.45;
  margin-bottom: var(--space-2);
  max-width: none;
}

.question-formula {
  font-family: var(--font-mono);
  background: var(--color-surface-2);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-3) var(--space-4);
  font-size: var(--text-sm);
  color: var(--color-primary);
  margin: var(--space-4) 0;
  display: block;
}

/* ============================================================
   ANSWER OPTIONS
   ============================================================ */

.options-grid {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  margin-top: var(--space-6);
}

.option-btn {
  display: flex;
  align-items: flex-start;
  gap: var(--space-4);
  padding: var(--space-4) var(--space-5);
  background: var(--color-surface);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-lg);
  cursor: pointer;
  text-align: left;
  width: 100%;
  transition: all var(--transition-interactive);
}

.option-btn:hover:not(:disabled) {
  border-color: var(--color-primary);
  background: var(--color-primary-highlight);
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.option-btn:disabled {
  cursor: default;
}

.option-btn.correct {
  border-color: var(--color-correct);
  background: var(--color-correct-bg);
}

.option-btn.wrong {
  border-color: var(--color-wrong);
  background: var(--color-wrong-bg);
}

.option-label {
  flex-shrink: 0;
  width: 28px;
  height: 28px;
  border-radius: var(--radius-full);
  background: var(--color-surface-2);
  border: 1.5px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: var(--text-sm);
  font-weight: 700;
  color: var(--color-text-muted);
  flex-shrink: 0;
  transition: all var(--transition-interactive);
}

.option-btn:hover:not(:disabled) .option-label {
  background: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
}

.option-btn.correct .option-label {
  background: var(--color-correct);
  color: #fff;
  border-color: var(--color-correct);
}

.option-btn.wrong .option-label {
  background: var(--color-wrong);
  color: #fff;
  border-color: var(--color-wrong);
}

.option-text {
  font-size: var(--text-base);
  color: var(--color-text);
  line-height: 1.5;
  padding-top: 2px;
}

/* ============================================================
   EXPLANATION PANEL
   ============================================================ */

.explanation-panel {
  background: var(--color-surface-2);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-5) var(--space-6);
  margin-top: var(--space-4);
  display: none;
  animation: slideDown 300ms cubic-bezier(0.16,1,0.3,1);
}

.explanation-panel.visible {
  display: block;
}

@keyframes slideDown {
  from { opacity: 0; transform: translateY(-8px); }
  to   { opacity: 1; transform: translateY(0); }
}

.explanation-label {
  font-size: var(--text-xs);
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-primary);
  margin-bottom: var(--space-2);
}

.explanation-text {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  line-height: 1.6;
}

/* ============================================================
   ACTION ROW
   ============================================================ */

.action-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  flex-wrap: wrap;
}

.hint-btn {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-full);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-text-muted);
  border: 1.5px solid var(--color-border);
  background: transparent;
}

.hint-btn:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.next-btn {
  background: var(--color-primary);
  color: #fff;
  padding: var(--space-3) var(--space-8);
  border-radius: var(--radius-full);
  font-size: var(--text-sm);
  font-weight: 700;
  border: none;
  display: none;
}

.next-btn.visible {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
}

.next-btn:hover { background: var(--color-primary-hover); }

/* ============================================================
   STATS STRIP
   ============================================================ */

.stats-strip {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-5) var(--space-6);
  display: flex;
  gap: var(--space-8);
  flex-wrap: wrap;
  margin-bottom: var(--space-6);
  box-shadow: var(--shadow-sm);
}

.stat-item {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
}

.stat-value {
  font-size: var(--text-xl);
  font-weight: 800;
  letter-spacing: -0.03em;
  color: var(--color-text);
  font-variant-numeric: tabular-nums;
  line-height: 1;
}

.stat-label {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-weight: 600;
}

/* ============================================================
   RESULTS SCREEN
   ============================================================ */

.results-screen {
  display: none;
  text-align: center;
  padding: var(--space-12) var(--space-6);
}

.results-screen.visible {
  display: block;
}

.results-score-ring {
  width: 140px;
  height: 140px;
  margin: 0 auto var(--space-6);
  position: relative;
}

.results-score-ring svg {
  transform: rotate(-90deg);
}

.score-ring-track {
  fill: none;
  stroke: var(--color-border);
  stroke-width: 10;
}

.score-ring-fill {
  fill: none;
  stroke: var(--color-primary);
  stroke-width: 10;
  stroke-linecap: round;
  stroke-dasharray: 339;
  stroke-dashoffset: 339;
  transition: stroke-dashoffset 1s cubic-bezier(0.16,1,0.3,1);
}

.score-ring-text {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.score-ring-pct {
  font-size: var(--text-xl);
  font-weight: 800;
  letter-spacing: -0.04em;
  color: var(--color-text);
  font-variant-numeric: tabular-nums;
  line-height: 1;
}

.score-ring-lbl {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  font-weight: 600;
}

.results-title {
  font-size: var(--text-xl);
  font-weight: 800;
  letter-spacing: -0.03em;
  color: var(--color-text);
  margin-bottom: var(--space-2);
}

.results-subtitle {
  font-size: var(--text-base);
  color: var(--color-text-muted);
  margin: 0 auto var(--space-8);
}

.results-actions {
  display: flex;
  gap: var(--space-3);
  justify-content: center;
  flex-wrap: wrap;
}

/* ============================================================
   SECTION TABS (AP / SAT toggle)
   ============================================================ */

.section-panel {
  display: none;
}

.section-panel.active {
  display: block;
}

/* ============================================================
   FOOTER
   ============================================================ */

.site-footer {
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
  padding: var(--space-8) var(--space-6);
  text-align: center;
}

.footer-inner {
  max-width: var(--content-wide);
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-3);
}

.footer-note {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
}

.footer-link {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  text-decoration: none;
}

.footer-link:hover { color: var(--color-primary); }

/* ============================================================
   RESPONSIVE
   ============================================================ */

@media (max-width: 600px) {
  .header-inner {
    padding: var(--space-3) var(--space-4);
    gap: var(--space-2);
  }

  .header-nav { gap: var(--space-1); }

  .nav-tab { padding: var(--space-2) var(--space-3); font-size: var(--text-xs); }

  .question-card { padding: var(--space-5); }

  .quiz-container { padding: var(--space-5) var(--space-4); }

  .stats-strip { gap: var(--space-5); }

  .action-row { flex-direction: column; align-items: stretch; }

  .next-btn { justify-content: center; }

  .progress-bar-track { width: 80px; }

  .hero h1 { font-size: clamp(1.5rem, 6vw, 2.5rem); }
}

/* ============================================================
   ANIMATIONS
   ============================================================ */

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(12px); }
  to   { opacity: 1; transform: translateY(0); }
}

.quiz-container {
  animation: fadeIn 300ms cubic-bezier(0.16,1,0.3,1);
}

/* Pulse on correct */
@keyframes correctPulse {
  0%   { box-shadow: 0 0 0 0 rgba(22,163,74,0.4); }
  70%  { box-shadow: 0 0 0 10px rgba(22,163,74,0); }
  100% { box-shadow: 0 0 0 0 rgba(22,163,74,0); }
}

.option-btn.correct {
  animation: correctPulse 600ms ease-out;
}

/* ============================================================
   AP VAULT v2 — NEW FEATURE STYLES
   Curriculum Page, Prev/Next Nav, Save & Resume, Study Guide
   ============================================================ */

/* ── SAVE PROGRESS BUTTON ─────────────────────────────────── */

.save-progress-btn {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-full);
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--color-text-muted);
  border: 1.5px solid var(--color-border);
  background: transparent;
  cursor: pointer;
  white-space: nowrap;
  transition: all var(--transition-interactive);
}

.save-progress-btn:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: var(--color-primary-highlight);
}

.btn-sm {
  padding: var(--space-2) var(--space-4);
  font-size: var(--text-xs);
}

/* ── CURRICULUM PAGE ──────────────────────────────────────── */

.curriculum-section {
  min-height: 60vh;
  padding: 0;
}

.curriculum-wrapper {
  max-width: var(--content-wide);
  margin: 0 auto;
  padding: var(--space-8) var(--space-6);
}

.curriculum-header {
  margin-bottom: var(--space-8);
}

.curriculum-heading {
  font-size: var(--text-xl);
  font-weight: 800;
  letter-spacing: -0.03em;
  color: var(--color-text);
  margin-bottom: var(--space-2);
}

.curriculum-subtitle {
  font-size: var(--text-base);
  color: var(--color-text-muted);
  max-width: 50ch;
}

.curriculum-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: var(--space-5);
}

.curriculum-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-6);
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
  transition: box-shadow var(--transition-interactive), transform var(--transition-interactive);
}

.curriculum-card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.curriculum-card-header {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.curriculum-card-icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.curriculum-card-info {
  flex: 1;
  min-width: 0;
}

.curriculum-card-title {
  font-size: var(--text-base);
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: var(--space-1);
}

.curriculum-card-meta {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.curriculum-progress-bar {
  height: 6px;
  background: var(--color-border);
  border-radius: var(--radius-full);
  overflow: hidden;
}

.curriculum-progress-fill {
  height: 100%;
  border-radius: var(--radius-full);
  transition: width 600ms cubic-bezier(0.16, 1, 0.3, 1);
  min-width: 0;
}

.curriculum-progress-label {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  font-weight: 600;
}

.curriculum-topics-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  border-top: 1px solid var(--color-divider);
  padding-top: var(--space-4);
}

.curriculum-topic-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  padding: var(--space-1) 0;
}

.curriculum-topic-name {
  font-size: var(--text-sm);
  color: var(--color-text);
  font-weight: 500;
}

.curriculum-topic-count {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  font-weight: 600;
  white-space: nowrap;
}

.curriculum-start-btn {
  margin-top: auto;
  width: 100%;
  justify-content: center;
}

/* ── RESUME BANNER ────────────────────────────────────────── */

.resume-banner {
  background: var(--color-primary-highlight);
  border: 1.5px solid var(--color-primary);
  border-radius: var(--radius-xl);
  padding: var(--space-5) var(--space-6);
  margin-bottom: var(--space-8);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  flex-wrap: wrap;
  animation: slideDown 300ms cubic-bezier(0.16, 1, 0.3, 1);
}

.resume-banner-content {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.resume-banner-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-lg);
  background: var(--color-primary);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.resume-banner-text {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
}

.resume-banner-text strong {
  font-size: var(--text-base);
  font-weight: 700;
  color: var(--color-text);
}

.resume-banner-text span {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
}

.resume-banner-actions {
  display: flex;
  gap: var(--space-2);
  flex-shrink: 0;
}

/* ── QUESTION NAVIGATOR DOTS ──────────────────────────────── */

.question-dots {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-bottom: var(--space-6);
  justify-content: center;
}

.q-dot {
  width: 28px;
  height: 28px;
  border-radius: var(--radius-full);
  border: 1.5px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text-faint);
  font-size: 11px;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-interactive);
  font-variant-numeric: tabular-nums;
  padding: 0;
}

.q-dot:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: var(--color-primary-highlight);
  transform: scale(1.1);
}

.q-dot-current {
  background: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(67, 56, 202, 0.2);
}

.q-dot-current:hover {
  background: var(--color-primary-hover);
  color: #fff;
  border-color: var(--color-primary-hover);
}

.q-dot-correct {
  background: var(--color-correct-bg);
  color: var(--color-correct);
  border-color: var(--color-correct);
}

.q-dot-correct:hover {
  background: var(--color-correct);
  color: #fff;
}

.q-dot-wrong {
  background: var(--color-wrong-bg);
  color: var(--color-wrong);
  border-color: var(--color-wrong);
}

.q-dot-wrong:hover {
  background: var(--color-wrong);
  color: #fff;
}

/* ── PREV/NEXT NAVIGATION ─────────────────────────────────── */

.action-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  flex-wrap: wrap;
}

.action-row-left {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  flex-wrap: wrap;
}

.prev-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-full);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-text-muted);
  border: 1.5px solid var(--color-border);
  background: transparent;
  cursor: pointer;
  transition: all var(--transition-interactive);
}

.prev-btn:hover:not(:disabled) {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.prev-btn-disabled,
.prev-btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

/* ── WAS-CHOSEN INDICATOR (revisiting answered question) ─── */

.option-btn.was-chosen {
  position: relative;
}

.option-btn.was-chosen::after {
  content: 'Your answer';
  position: absolute;
  top: var(--space-1);
  right: var(--space-3);
  font-size: 10px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text-faint);
  opacity: 0.7;
}

/* ── STUDY GUIDE PANEL ────────────────────────────────────── */

.study-guide-panel {
  max-height: 0;
  overflow: hidden;
  transition: max-height 400ms cubic-bezier(0.16, 1, 0.3, 1), opacity 300ms ease, margin 300ms ease;
  opacity: 0;
  margin-bottom: 0;
}

.study-guide-panel.sg-open {
  max-height: 2000px;
  opacity: 1;
  margin-bottom: var(--space-4);
}

.study-guide-inner {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-left: 4px solid var(--color-primary);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  box-shadow: var(--shadow-sm);
}

.sg-heading {
  font-size: var(--text-lg);
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: var(--space-5);
  padding-bottom: var(--space-3);
  border-bottom: 1px solid var(--color-divider);
}

.sg-section {
  margin-bottom: var(--space-5);
}

.sg-section-label {
  font-size: var(--text-xs);
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-primary);
  margin-bottom: var(--space-3);
}

.sg-concepts {
  list-style: none;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.sg-concepts li {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  line-height: 1.6;
  padding-left: var(--space-5);
  position: relative;
  max-width: none;
}

.sg-concepts li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.5em;
  width: 6px;
  height: 6px;
  border-radius: var(--radius-full);
  background: var(--color-primary);
}

.sg-example {
  background: var(--color-surface-2);
  border: 1px solid var(--color-divider);
  border-radius: var(--radius-md);
  padding: var(--space-4);
  margin-bottom: var(--space-3);
}

.sg-example-title {
  font-size: var(--text-sm);
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: var(--space-2);
}

.sg-example-steps {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  line-height: 1.6;
  font-family: var(--font-mono);
}

.sg-mistakes {
  background: var(--color-wrong-bg);
  border: 1px solid var(--color-wrong);
  border-radius: var(--radius-md);
  padding: var(--space-4);
}

.sg-mistakes-label {
  font-size: var(--text-sm);
  font-weight: 700;
  color: var(--color-wrong);
  margin-bottom: var(--space-2);
}

.sg-mistakes p {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  line-height: 1.6;
  max-width: none;
}

/* ── TOAST NOTIFICATION ───────────────────────────────────── */

.apv-toast {
  position: fixed;
  bottom: var(--space-6);
  right: var(--space-6);
  background: var(--color-surface);
  color: var(--color-text);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-3) var(--space-5);
  font-size: var(--text-sm);
  font-weight: 600;
  box-shadow: var(--shadow-lg);
  z-index: 1000;
  transition: transform 300ms cubic-bezier(0.16, 1, 0.3, 1), opacity 300ms ease;
}

.apv-toast-enter {
  transform: translateY(20px);
  opacity: 0;
}

.apv-toast-visible {
  transform: translateY(0);
  opacity: 1;
}

.apv-toast-exit {
  transform: translateY(20px);
  opacity: 0;
}

/* ── RESPONSIVE — v2 additions ────────────────────────────── */

@media (max-width: 600px) {
  .curriculum-grid {
    grid-template-columns: 1fr;
  }

  .curriculum-wrapper {
    padding: var(--space-5) var(--space-4);
  }

  .resume-banner {
    flex-direction: column;
    align-items: flex-start;
  }

  .resume-banner-actions {
    width: 100%;
  }

  .resume-banner-actions .btn {
    flex: 1;
    justify-content: center;
  }

  .question-dots {
    gap: var(--space-1);
  }

  .q-dot {
    width: 26px;
    height: 26px;
    font-size: 10px;
  }

  .action-row-left {
    width: 100%;
    justify-content: space-between;
  }

  .action-row {
    flex-direction: column;
    align-items: stretch;
  }

  .next-btn {
    justify-content: center;
  }

  .prev-btn {
    font-size: var(--text-xs);
    padding: var(--space-2) var(--space-3);
  }

  .study-guide-inner {
    padding: var(--space-4);
  }

  .save-label {
    display: none;
  }

  .save-progress-btn {
    padding: var(--space-2);
  }

  .apv-toast {
    left: var(--space-4);
    right: var(--space-4);
    bottom: var(--space-4);
    text-align: center;
  }
}

/* ── VIDEO TUTORIAL SECTION ─── */
.sg-video-section { padding: 12px 0 0; border-top: 1px solid var(--color-border); margin-top: 10px; }
.sg-video-toggle {
  background: var(--color-surface-alt);
  border: 1px solid var(--color-border);
  color: var(--color-text-muted);
  font-size: 11px;
  font-family: inherit;
  padding: 4px 10px;
  border-radius: 4px;
  cursor: pointer;
  margin-top: 4px;
  width: 100%;
  text-align: left;
  transition: background 0.15s;
}
.sg-video-toggle:hover { background: var(--color-border); }
.sg-video-embed {
  margin-top: 8px;
  border-radius: 6px;
  overflow: hidden;
  aspect-ratio: 16/9;
  background: #000;
}
.sg-video-embed iframe {
  width: 100%;
  height: 100%;
  display: block;
}

/* ── CURRICULUM META CHIPS ─── */
.curriculum-header-row { display: flex; align-items: flex-start; justify-content: space-between; gap: 12px; flex-wrap: wrap; }
.curriculum-meta-chips { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 4px; }
.chip { display: flex; align-items: center; gap: 4px; padding: 4px 10px; border-radius: 20px; font-size: 11px; font-weight: 600; white-space: nowrap; }
.chip-countdown { background: #ede9fe; color: #4c1d95; }
.chip-streak { background: #fff7ed; color: #92400e; }
[data-theme="dark"] .chip-countdown { background: #2e1065; color: #c4b5fd; }
[data-theme="dark"] .chip-streak { background: #1c1107; color: #fbbf24; }

/* ── WEAK FLAG ─── */
.weak-flag {
  display: inline-block;
  background: #fef2f2;
  color: #dc2626;
  font-size: 9px;
  font-weight: 700;
  padding: 1px 5px;
  border-radius: 3px;
  margin-left: 4px;
  vertical-align: middle;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}
[data-theme="dark"] .weak-flag { background: #3b0a0a; color: #fca5a5; }