/* ==========================================================================
   INSIEMILAB - STILE GLOBALE & DESIGN SYSTEM
   Modern, Accessible, Responsive & Interactive Math Lab
   ========================================================================== */

:root {
  /* Color Palette - Stile Grafico Chiaro & Luminoso (High Legibility & Modern Education) */
  --bg-primary: #f8fafc;          /* Sfondo pulito, chiaro e riposante */
  --bg-secondary: #ffffff;        /* Bianco puro per carte ed elementi in primo piano */
  --bg-tertiary: #f1f5f9;         /* Grigio chiarissimo per sfondi secondari */
  --bg-card: #ffffff;
  --bg-card-hover: #ffffff;
  
  --text-primary: #0f172a;        /* Grigio ardesia scuro ad altissimo contrasto */
  --text-secondary: #334155;      /* Testo secondario chiaro e nitido */
  --text-muted: #64748b;          /* Dettagli e didascalie leggibili */
  --text-inverse: #ffffff;

  --accent-primary: #4338ca;      /* Indaco brillante ad alta visibilità */
  --accent-primary-hover: #3730a3;
  --accent-primary-light: #eef2ff;
  --accent-secondary: #0284c7;    /* Blu cielo saturo */
  --accent-secondary-light: #f0f9ff;
  --accent-purple: #7e22ce;
  --accent-purple-light: #faf5ff;
  
  --set-a-color: #2563eb;        /* Blu reale vivido per Insieme A */
  --set-a-bg: rgba(37, 99, 235, 0.16);
  --set-b-color: #e11d48;        /* Rosso rubino vivido per Insieme B */
  --set-b-bg: rgba(225, 29, 72, 0.16);
  --intersection-color: #7c3aed;  /* Viola intenso per Intersezione */
  --intersection-bg: rgba(124, 58, 237, 0.25);
  --universe-color: #475569;     /* Bordo Universo netto */
  --universe-bg: #f8fafc;

  --success: #059669;
  --success-light: #ecfdf5;
  --danger: #dc2626;
  --danger-light: #fef2f2;
  --warning: #d97706;
  --warning-light: #fffbeb;
  --info: #0284c7;
  --info-light: #f0f9ff;

  --border-light: #e2e8f0;       /* Bordi nitidi e puliti */
  --border-subtle: #cbd5e1;
  --shadow-sm: 0 1px 3px rgba(15, 23, 42, 0.04);
  --shadow-md: 0 4px 14px rgba(15, 23, 42, 0.06);
  --shadow-lg: 0 10px 28px rgba(15, 23, 42, 0.08);
  --shadow-xl: 0 20px 40px rgba(15, 23, 42, 0.10);

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --radius-full: 9999px;

  --font-sans: 'Plus Jakarta Sans', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', Menlo, monospace;

  --header-height: 72px;
  --max-content-width: 1240px;
  --transition-fast: 0.18s cubic-bezier(0.16, 1, 0.3, 1);
  --transition-normal: 0.28s cubic-bezier(0.16, 1, 0.3, 1);
}

[data-theme="dark"] {
  --bg-primary: #090d16;
  --bg-secondary: #111827;
  --bg-tertiary: #1e293b;
  --bg-card: #141d2e;
  --bg-card-hover: #1b263b;
  
  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --text-inverse: #090d16;

  --accent-primary: #6366f1;
  --accent-primary-hover: #818cf8;
  --accent-primary-light: rgba(99, 102, 241, 0.18);
  --accent-secondary: #38bdf8;
  --accent-secondary-light: rgba(56, 189, 248, 0.18);
  --accent-purple: #c084fc;
  --accent-purple-light: rgba(192, 132, 252, 0.18);

  --set-a-color: #60a5fa;
  --set-a-bg: rgba(96, 165, 250, 0.25);
  --set-b-color: #f87171;
  --set-b-bg: rgba(248, 113, 113, 0.25);
  --intersection-color: #a78bfa;
  --intersection-bg: rgba(167, 139, 250, 0.38);
  --universe-color: #94a3b8;
  --universe-bg: rgba(148, 163, 184, 0.08);

  --border-light: #243048;
  --border-subtle: #334155;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.35);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.45);
  --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.55);
}

/* Modalità LIM / Lavagna Interattiva (font e controlli ingranditi) */
body.mode-lim {
  font-size: 1.14rem;
  --max-content-width: 1400px;
}
body.mode-lim .btn, body.mode-lim .tab-btn {
  padding: 12px 24px;
  font-size: 1.08rem;
}
body.mode-lim .card {
  padding: 28px;
}

/* ==========================================================================
   RESET & BASE
   ========================================================================== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  background-image: radial-gradient(rgba(148, 163, 184, 0.25) 1px, transparent 1px);
  background-size: 24px 24px;
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
  transition: background-color var(--transition-normal), color var(--transition-normal);
}

a {
  color: var(--accent-primary);
  text-decoration: none;
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  outline: none;
  background: none;
}

input, select, textarea {
  font-family: inherit;
  font-size: inherit;
  color: inherit;
  border: 1px solid var(--border-light);
  background-color: var(--bg-secondary);
  border-radius: var(--radius-sm);
  padding: 10px 14px;
}
input:focus, select:focus, textarea:focus {
  outline: 2px solid var(--accent-primary);
  border-color: transparent;
}

/* ==========================================================================
   HEADER & NAVBAR
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border-light);
  transition: background-color var(--transition-normal), border-color var(--transition-normal);
}
[data-theme="dark"] .site-header {
  background: rgba(17, 24, 39, 0.85);
}

.header-inner {
  max-width: var(--max-content-width);
  margin: 0 auto;
  padding: 12px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.brand-icon {
  width: 44px;
  height: 44px;
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
  color: white;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 1.4rem;
  box-shadow: 0 4px 10px rgba(79, 70, 229, 0.3);
}

.brand-text h1 {
  font-size: 1.25rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.2;
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.brand-text p {
  font-size: 0.78rem;
  color: var(--text-muted);
  font-weight: 500;
}

.header-controls {
  display: flex;
  align-items: center;
  gap: 10px;
}

.tool-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 14px;
  border-radius: var(--radius-full);
  background: var(--bg-tertiary);
  color: var(--text-secondary);
  font-size: 0.86rem;
  font-weight: 600;
  transition: all var(--transition-fast);
  border: 1px solid var(--border-light);
}
.tool-btn:hover {
  background: var(--accent-primary-light);
  color: var(--accent-primary);
  border-color: var(--accent-primary);
  transform: translateY(-1px);
}
.tool-btn.active {
  background: var(--accent-primary);
  color: white;
  border-color: var(--accent-primary);
}

/* ==========================================================================
   NAVIGATION TABS
   ========================================================================== */
.nav-tabs-wrapper {
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border-light);
  position: sticky;
  top: 70px;
  z-index: 90;
}

.nav-tabs {
  max-width: var(--max-content-width);
  margin: 0 auto;
  padding: 8px 20px;
  display: flex;
  gap: 8px;
  overflow-x: auto;
  scrollbar-width: none;
}
.nav-tabs::-webkit-scrollbar {
  display: none;
}

.tab-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 18px;
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  font-size: 0.92rem;
  font-weight: 600;
  white-space: nowrap;
  transition: all var(--transition-fast);
  border: 1px solid transparent;
}

.tab-btn:hover {
  background: var(--bg-tertiary);
  color: var(--text-primary);
}

.tab-btn.active {
  background: var(--accent-primary-light);
  color: var(--accent-primary);
  border-color: rgba(79, 70, 229, 0.3);
}

.tab-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 20px;
  height: 20px;
  border-radius: var(--radius-full);
  background: var(--bg-tertiary);
  font-size: 0.74rem;
  font-weight: 700;
}
.tab-btn.active .tab-badge {
  background: var(--accent-primary);
  color: white;
}

/* ==========================================================================
   MAIN CONTENT & SECTIONS
   ========================================================================== */
.main-container {
  max-width: var(--max-content-width);
  margin: 0 auto;
  padding: 32px 20px 80px;
  width: 100%;
  flex: 1;
}

.tab-section {
  display: none;
  animation: fadeIn 0.35s ease;
}
.tab-section.active {
  display: block;
}

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

/* SECTION HEADER BANNER */
.section-hero {
  background: linear-gradient(135deg, #eef2ff 0%, #f0f9ff 100%);
  border: 1px solid #dbeafe;
  border-radius: var(--radius-lg);
  padding: 28px 32px;
  margin-bottom: 28px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  box-shadow: 0 2px 8px rgba(15, 23, 42, 0.03);
}
.section-hero-content h2 {
  font-size: 1.85rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 8px;
  color: var(--text-primary);
}
.section-hero-content p {
  color: var(--text-secondary);
  font-size: 1.05rem;
  max-width: 800px;
}

.hero-pill {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 12px;
  border-radius: var(--radius-full);
  background: var(--accent-primary-light);
  color: var(--accent-primary);
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 10px;
  border: 1px solid #c7d2fe;
}

/* ==========================================================================
   CARDS & GRIDS
   ========================================================================== */
.grid-2 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(360px, 1fr));
  gap: 24px;
  margin-bottom: 28px;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 20px;
  margin-bottom: 28px;
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 24px;
  box-shadow: 0 2px 6px rgba(15, 23, 42, 0.03), 0 8px 20px rgba(15, 23, 42, 0.02);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast), border-color var(--transition-fast);
}
.card:hover {
  box-shadow: 0 4px 12px rgba(15, 23, 42, 0.05), 0 16px 28px rgba(15, 23, 42, 0.03);
  border-color: var(--border-subtle);
}

.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
}

.card-title {
  font-size: 1.25rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--text-primary);
}

.card-title .icon {
  font-size: 1.4rem;
}

/* ==========================================================================
   DIDACTIC CALLOUTS & PILLS
   ========================================================================== */
.callout {
  padding: 16px 20px;
  border-radius: var(--radius-md);
  margin: 16px 0;
  display: flex;
  gap: 14px;
  align-items: flex-start;
  border-left: 4px solid transparent;
}
.callout-icon {
  font-size: 1.4rem;
  flex-shrink: 0;
  line-height: 1.2;
}
.callout.info {
  background: var(--info-light);
  border-left-color: var(--info);
  color: #0369a1;
}
[data-theme="dark"] .callout.info {
  background: rgba(2, 132, 199, 0.15);
  color: #7dd3fc;
}

.callout.success {
  background: var(--success-light);
  border-left-color: var(--success);
  color: #065f46;
}
[data-theme="dark"] .callout.success {
  background: rgba(16, 185, 129, 0.15);
  color: #6ee7b7;
}

.callout.warning {
  background: var(--warning-light);
  border-left-color: var(--warning);
  color: #92400e;
}
[data-theme="dark"] .callout.warning {
  background: rgba(245, 158, 11, 0.15);
  color: #fcd34d;
}

.math-badge {
  display: inline-block;
  font-family: var(--font-mono);
  background: #ffffff;
  padding: 4px 10px;
  border-radius: 6px;
  font-weight: 700;
  color: var(--accent-primary);
  border: 1.5px solid #c7d2fe;
  box-shadow: 0 1px 3px rgba(15, 23, 42, 0.04);
}

/* ==========================================================================
   MODULO 1: COLLEZIONE VS INSIEME (SIMULATORE)
   ========================================================================== */
.judge-container {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.phrase-picker {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 12px;
}

.phrase-chip {
  padding: 8px 14px;
  border-radius: var(--radius-full);
  background: var(--bg-tertiary);
  border: 1px solid var(--border-light);
  color: var(--text-secondary);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
}
.phrase-chip:hover {
  background: var(--accent-primary-light);
  border-color: var(--accent-primary);
  color: var(--accent-primary);
}
.phrase-chip.active {
  background: var(--accent-primary);
  color: white;
  border-color: var(--accent-primary);
  box-shadow: 0 4px 10px rgba(79, 70, 229, 0.3);
}

.judge-tester-box {
  background: var(--bg-tertiary);
  border-radius: var(--radius-md);
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.custom-input-row {
  display: flex;
  gap: 10px;
}
.custom-input-row input {
  flex: 1;
}

.verdict-card {
  padding: 20px;
  border-radius: var(--radius-md);
  border: 2px solid transparent;
  display: flex;
  flex-direction: column;
  gap: 10px;
  transition: all var(--transition-normal);
}
.verdict-card.is-set {
  background: var(--success-light);
  border-color: var(--success);
  color: #064e3b;
}
[data-theme="dark"] .verdict-card.is-set {
  background: rgba(16, 185, 129, 0.15);
  color: #a7f3d0;
}

.verdict-card.not-set {
  background: var(--danger-light);
  border-color: var(--danger);
  color: #7f1d1d;
}
[data-theme="dark"] .verdict-card.not-set {
  background: rgba(239, 68, 68, 0.15);
  color: #fecaca;
}

.verdict-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.verdict-badge {
  font-size: 0.95rem;
  font-weight: 800;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  text-transform: uppercase;
}

.criteria-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-top: 10px;
}
.criteria-item {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 0.92rem;
  font-weight: 600;
}
.criteria-status {
  width: 22px;
  height: 22px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8rem;
  font-weight: 800;
  color: white;
}
.criteria-item.pass .criteria-status { background: var(--success); }
.criteria-item.fail .criteria-status { background: var(--danger); }

/* ==========================================================================
   MODULO 2: LE 3 RAPPRESENTAZIONI
   ========================================================================== */
.rep-comparison-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
  margin-top: 20px;
}
@media (max-width: 900px) {
  .rep-comparison-grid {
    grid-template-columns: 1fr;
  }
}

.rep-box {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 18px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.rep-box-title {
  font-weight: 700;
  font-size: 1rem;
  color: var(--accent-primary);
  display: flex;
  align-items: center;
  gap: 8px;
}

.rep-content {
  font-family: var(--font-mono);
  background: var(--bg-secondary);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-sm);
  padding: 14px;
  font-size: 1rem;
  min-height: 80px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  word-break: break-word;
}

.venn-single-preview {
  width: 100%;
  height: 180px;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* ==========================================================================
   MODULO 3: LABORATORIO OPERAZIONI (VENN INTERATTIVO)
   ========================================================================== */
.op-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 20px;
}

.op-btn {
  padding: 10px 18px;
  border-radius: var(--radius-md);
  background: var(--bg-secondary);
  border: 1px solid var(--border-light);
  color: var(--text-secondary);
  font-weight: 700;
  font-size: 0.94rem;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  transition: all var(--transition-fast);
}
.op-btn:hover {
  background: var(--bg-tertiary);
  color: var(--text-primary);
}
.op-btn.active {
  background: var(--accent-primary);
  color: white;
  border-color: var(--accent-primary);
  box-shadow: 0 4px 12px rgba(79, 70, 229, 0.3);
}

.lab-workspace {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 24px;
  align-items: start;
}
@media (max-width: 960px) {
  .lab-workspace {
    grid-template-columns: 1fr;
  }
}

.venn-display-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 24px;
  display: flex;
  flex-direction: column;
  align-items: center;
  position: relative;
}

.venn-svg-wrapper {
  width: 100%;
  max-width: 460px;
  height: 320px;
  position: relative;
  margin: 10px 0;
}

.venn-svg {
  width: 100%;
  height: 100%;
}

.venn-region {
  cursor: pointer;
  transition: fill var(--transition-fast), opacity var(--transition-fast);
}
.venn-region:hover {
  filter: brightness(1.1);
}

.venn-region-label {
  font-family: var(--font-sans);
  font-weight: 800;
  font-size: 16px;
  pointer-events: none;
  user-select: none;
}

.venn-element-node {
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 700;
  fill: var(--text-primary);
  pointer-events: none;
}

.op-details-card {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.formula-banner {
  background: linear-gradient(135deg, #f5f3ff 0%, #eff6ff 100%);
  border: 1.5px solid #c7d2fe;
  border-radius: var(--radius-md);
  padding: 18px 24px;
  text-align: center;
  box-shadow: 0 2px 6px rgba(67, 56, 202, 0.04);
}
.formula-banner .formula-math {
  font-family: var(--font-mono);
  font-size: 1.55rem;
  font-weight: 800;
  color: var(--accent-primary);
  letter-spacing: 0.02em;
}
.formula-banner .formula-desc {
  font-size: 0.92rem;
  color: var(--text-secondary);
  margin-top: 6px;
  font-weight: 500;
}

.set-elements-editor {
  display: flex;
  flex-direction: column;
  gap: 12px;
  background: var(--bg-tertiary);
  padding: 16px;
  border-radius: var(--radius-md);
}

.element-input-group {
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.element-input-group label {
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: 6px;
}
.color-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  display: inline-block;
}
.dot-a { background: var(--set-a-color); }
.dot-b { background: var(--set-b-color); }
.dot-u { background: var(--universe-color); }

.result-box {
  background: var(--bg-secondary);
  border: 2px dashed var(--accent-primary);
  border-radius: var(--radius-md);
  padding: 14px 18px;
}
.result-box-title {
  font-size: 0.82rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--accent-primary);
  margin-bottom: 4px;
}
.result-box-elements {
  font-family: var(--font-mono);
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
}

/* ==========================================================================
   MODULO 4: PRODOTTO CARTESIANO & RELAZIONI
   ========================================================================== */
.cartesian-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-bottom: 20px;
}

.view-selector-tabs {
  display: flex;
  gap: 6px;
  background: var(--bg-tertiary);
  padding: 4px;
  border-radius: var(--radius-md);
  margin-bottom: 16px;
}
.view-btn {
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 0.88rem;
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}
.view-btn.active {
  background: var(--bg-secondary);
  color: var(--accent-primary);
  box-shadow: var(--shadow-sm);
}

.cartesian-display-area {
  min-height: 280px;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow-x: auto;
  padding: 16px 0;
}

/* Tabella a doppia entrata */
.cartesian-table {
  border-collapse: collapse;
  margin: 0 auto;
}
.cartesian-table th, .cartesian-table td {
  border: 1px solid var(--border-light);
  padding: 10px 18px;
  text-align: center;
  font-family: var(--font-mono);
}
.cartesian-table th {
  background: var(--bg-tertiary);
  font-weight: 800;
  color: var(--accent-primary);
}
.cartesian-table td {
  background: var(--bg-secondary);
  font-size: 0.95rem;
  transition: background var(--transition-fast);
}
.cartesian-table td:hover {
  background: var(--accent-primary-light);
  color: var(--accent-primary);
  font-weight: 700;
}

/* Diagramma ad albero */
.tree-diagram {
  display: flex;
  flex-direction: column;
  gap: 16px;
  width: 100%;
  max-width: 500px;
}
.tree-node-row {
  display: flex;
  align-items: center;
  gap: 20px;
}
.tree-root {
  background: var(--set-a-color);
  color: white;
  padding: 6px 14px;
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-weight: 700;
}
.tree-branches {
  display: flex;
  flex-direction: column;
  gap: 8px;
  border-left: 2px solid var(--border-subtle);
  padding-left: 14px;
}
.tree-branch-item {
  display: flex;
  align-items: center;
  gap: 10px;
}
.tree-pair {
  font-family: var(--font-mono);
  background: var(--accent-primary-light);
  color: var(--accent-primary);
  padding: 3px 10px;
  border-radius: var(--radius-sm);
  font-weight: 600;
}

/* Piano Cartesiano Discreto */
.discrete-grid-svg {
  max-width: 460px;
  width: 100%;
  height: 300px;
}

/* ==========================================================================
   MODULO 5: PALESTRA ESERCIZI RIPETIBILI
   ========================================================================== */
.gym-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px;
  margin-bottom: 24px;
}

.score-tracker-banner {
  display: flex;
  align-items: center;
  gap: 20px;
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  padding: 10px 20px;
  border-radius: var(--radius-full);
}
.score-stat {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.95rem;
  font-weight: 700;
}
.score-num {
  font-size: 1.25rem;
  color: var(--accent-primary);
}

.exercise-nav-pills {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 24px;
}
.ex-pill {
  padding: 8px 16px;
  border-radius: var(--radius-full);
  background: var(--bg-tertiary);
  border: 1px solid var(--border-light);
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}
.ex-pill:hover {
  background: var(--accent-primary-light);
  color: var(--accent-primary);
}
.ex-pill.active {
  background: var(--accent-primary);
  color: white;
  border-color: var(--accent-primary);
}

/* Sub-nav chips per gli esercizi filtrati */
.exercise-subnav {
  display: flex;
  align-items: center;
  gap: 8px;
  overflow-x: auto;
  padding: 4px 2px 14px 2px;
  margin-bottom: 20px;
  scrollbar-width: thin;
}
.subnav-chip {
  padding: 6px 14px;
  border-radius: var(--radius-sm);
  background: var(--bg-tertiary);
  border: 1px solid var(--border-light);
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--text-secondary);
  cursor: pointer;
  white-space: nowrap;
  transition: all var(--transition-fast);
  display: inline-flex;
  align-items: center;
  gap: 6px;
}
.subnav-chip:hover {
  border-color: var(--accent-primary);
  color: var(--accent-primary);
  background: var(--accent-primary-light);
}
.subnav-chip.active {
  background: var(--accent-primary);
  color: white;
  border-color: var(--accent-primary);
  box-shadow: var(--shadow-sm);
}
.subnav-chip.solved {
  border-color: #10b981;
}
.subnav-chip.solved::after {
  content: '✓';
  color: #10b981;
  font-weight: 800;
  margin-left: 2px;
}
.subnav-chip.active.solved::after {
  color: #ffffff;
}

.exercise-box {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 28px;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.exercise-title-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--border-light);
  padding-bottom: 14px;
}
.exercise-type-tag {
  font-size: 0.8rem;
  text-transform: uppercase;
  font-weight: 800;
  color: var(--accent-primary);
  letter-spacing: 0.05em;
}

.exercise-question {
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--text-primary);
}

.options-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 12px;
}

.option-btn {
  background: var(--bg-secondary);
  border: 1.5px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 16px 20px;
  text-align: left;
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
  transition: all var(--transition-fast);
  display: flex;
  align-items: center;
  gap: 12px;
  box-shadow: 0 1px 3px rgba(15, 23, 42, 0.03);
}
.option-btn:hover {
  border-color: var(--accent-primary);
  background: var(--accent-primary-light);
  color: var(--accent-primary);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(67, 56, 202, 0.08);
}
.option-btn.selected {
  border-color: var(--accent-primary);
  background: var(--accent-primary-light);
  color: var(--accent-primary);
  box-shadow: 0 0 0 2px var(--accent-primary);
}
.option-btn.correct {
  border-color: var(--success);
  background: var(--success-light);
  color: #064e3b;
  box-shadow: 0 0 0 2px var(--success);
}
.option-btn.wrong {
  border-color: var(--danger);
  background: var(--danger-light);
  color: #7f1d1d;
  box-shadow: 0 0 0 2px var(--danger);
}

.feedback-banner {
  padding: 16px 20px;
  border-radius: var(--radius-md);
  display: none;
  font-size: 0.98rem;
  animation: fadeIn 0.25s ease;
}
.feedback-banner.show {
  display: block;
}
.feedback-banner.correct {
  background: var(--success-light);
  border: 1px solid var(--success);
  color: #064e3b;
}
[data-theme="dark"] .feedback-banner.correct {
  background: rgba(16, 185, 129, 0.2);
  color: #6ee7b7;
}
.feedback-banner.wrong {
  background: var(--danger-light);
  border: 1px solid var(--danger);
  color: #7f1d1d;
}
[data-theme="dark"] .feedback-banner.wrong {
  background: rgba(239, 68, 68, 0.2);
  color: #fca5a5;
}

.exercise-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  border-top: 1px solid var(--border-light);
  padding-top: 18px;
}

/* ==========================================================================
   MODULO 6: STORIA & I FONDAMENTI DELLA MATEMATICA
   ========================================================================== */
.history-timeline {
  display: flex;
  flex-direction: column;
  gap: 28px;
  position: relative;
  padding-left: 30px;
  margin: 32px 0;
}
.history-timeline::before {
  content: '';
  position: absolute;
  left: 9px;
  top: 10px;
  bottom: 10px;
  width: 2px;
  background: var(--accent-primary-light);
}

.timeline-item {
  position: relative;
}
.timeline-dot {
  position: absolute;
  left: -30px;
  top: 4px;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--accent-primary);
  border: 3px solid var(--bg-card);
  box-shadow: 0 0 0 2px var(--accent-primary);
}

.foundation-pillars-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
  margin: 24px 0;
}

.pillar-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 24px;
  position: relative;
  overflow: hidden;
}
.pillar-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--accent-primary), var(--accent-secondary));
}

.math-reduction-table {
  width: 100%;
  border-collapse: collapse;
  margin: 20px 0;
}
.math-reduction-table th, .math-reduction-table td {
  padding: 14px 18px;
  border: 1px solid var(--border-light);
  text-align: left;
}
.math-reduction-table th {
  background: var(--bg-tertiary);
  font-weight: 700;
  color: var(--accent-primary);
}
.math-reduction-table td:first-child {
  font-weight: 700;
  color: var(--text-primary);
}

/* ==========================================================================
   BUTTONS & CONTROLS GENERALI
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 20px;
  border-radius: var(--radius-md);
  font-weight: 700;
  font-size: 0.95rem;
  transition: all var(--transition-fast);
}

.btn-primary {
  background: var(--accent-primary);
  color: white;
  box-shadow: 0 4px 12px rgba(79, 70, 229, 0.25);
}
.btn-primary:hover {
  background: var(--accent-primary-hover);
  transform: translateY(-1px);
  box-shadow: 0 6px 16px rgba(79, 70, 229, 0.35);
}

.btn-secondary {
  background: var(--bg-tertiary);
  color: var(--text-primary);
  border: 1px solid var(--border-light);
}
.btn-secondary:hover {
  background: var(--border-light);
  color: var(--text-primary);
}

.btn-success {
  background: var(--success);
  color: white;
}
.btn-success:hover {
  background: #059669;
}

.btn-sm {
  padding: 6px 14px;
  font-size: 0.84rem;
}

/* ==========================================================================
   FOOTER
   ========================================================================== */
.site-footer {
  border-top: 1px solid var(--border-light);
  background: var(--bg-secondary);
  padding: 28px 20px;
  font-size: 0.88rem;
  color: var(--text-muted);
}
.footer-inner {
  max-width: var(--max-content-width);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px;
}

/* ==========================================================================
   ACCESSIBILITY & UTILITIES
   ========================================================================== */
.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;
}

@media (max-width: 768px) {
  .section-hero {
    padding: 20px;
    flex-direction: column;
    align-items: flex-start;
  }
  .section-hero-content h2 {
    font-size: 1.5rem;
  }
  .grid-2 {
    grid-template-columns: 1fr;
  }
}