/* ==========================================================================
   Apple Design System - Math Teacher
   Colores Principales:
     - Fondo: #EFFDFE
     - Seleccionado / Activo: #AF125A
   Estilo: Sombras suaves multicapa, bordes invisibles/sutiles, tipografía limpia
   ========================================================================== */

:root {
  --bg-canvas: #EFFDFE;
  --color-primary: #AF125A;
  --color-primary-hover: #960f4c;
  --color-primary-light: rgba(175, 18, 90, 0.08);
  --color-primary-glow: rgba(175, 18, 90, 0.22);
  
  --card-bg: rgba(255, 255, 255, 0.88);
  --card-bg-solid: #FFFFFF;
  --text-main: #1D1D1F;
  --text-secondary: #6E6E73;
  --text-tertiary: #86868B;
  
  --color-success: #34C759;
  --color-success-bg: #EAFBF0;
  --color-error: #FF3B30;
  --color-error-bg: #FEECEB;
  --color-warning: #FF9500;
  --color-warning-bg: #FFF8EB;
  
  --radius-xl: 24px;
  --radius-lg: 18px;
  --radius-md: 12px;
  --radius-sm: 8px;
  
  --shadow-subtle: 0 2px 8px -2px rgba(15, 23, 42, 0.04), 0 1px 4px -1px rgba(15, 23, 42, 0.02);
  --shadow-card: 0 8px 30px -4px rgba(15, 23, 42, 0.06), 0 4px 12px -2px rgba(15, 23, 42, 0.03);
  --shadow-hover: 0 14px 40px -6px rgba(15, 23, 42, 0.1), 0 6px 16px -3px rgba(15, 23, 42, 0.04);
  --shadow-primary: 0 2px 8px rgba(0, 0, 0, 0.08), 0 1px 3px rgba(0, 0, 0, 0.04);

  --transition-smooth: all 0.26s cubic-bezier(0.16, 1, 0.3, 1);
}

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text", "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background-color: var(--bg-canvas);
  color: var(--text-main);
  min-height: 100vh;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  padding-bottom: 110px;
}

/* Envoltorio Principal Responsive */
.app-container {
  max-width: 980px;
  margin: 0 auto;
  padding: 24px 16px;
}

/* Header & Barra Superior */
.app-header {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  margin-bottom: 24px;
}

.brand-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  background: rgba(255, 255, 255, 0.7);
  backdrop-filter: blur(12px);
  border-radius: 999px;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-primary);
  box-shadow: var(--shadow-subtle);
  margin-bottom: 12px;
}

.app-title {
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  color: var(--text-main);
  text-wrap: balance;
}

.app-subtitle {
  font-size: clamp(0.95rem, 2vw, 1.1rem);
  color: var(--text-secondary);
  margin-top: 6px;
  max-width: 600px;
}

/* Barra de Estadísticas Apple */
.stats-bar {
  display: flex;
  justify-content: center;
  gap: 12px;
  margin-top: 16px;
  flex-wrap: wrap;
}

.stat-pill {
  background: var(--card-bg-solid);
  padding: 8px 18px;
  border-radius: 999px;
  box-shadow: var(--shadow-subtle);
  font-size: 0.88rem;
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: 8px;
  transition: var(--transition-smooth);
}

.stat-icon {
  color: var(--color-primary);
  flex-shrink: 0;
}

.stat-pill strong {
  font-weight: 700;
  color: var(--color-primary);
}

/* Navegación por Pestañas Apple Segmented Control */
.segmented-nav {
  display: flex;
  background: rgba(255, 255, 255, 0.75);
  backdrop-filter: blur(16px);
  padding: 5px;
  border-radius: 999px;
  box-shadow: var(--shadow-subtle);
  margin-bottom: 28px;
  gap: 4px;
  overflow-x: auto;
  scrollbar-width: none;
}
.segmented-nav::-webkit-scrollbar {
  display: none;
}

.segment-btn {
  flex: 1;
  min-width: 130px;
  padding: 10px 18px;
  border: none;
  background: transparent;
  color: var(--text-secondary);
  font-size: 0.92rem;
  font-weight: 600;
  border-radius: 999px;
  cursor: pointer;
  transition: var(--transition-smooth);
  white-space: nowrap;
  text-align: center;
}

.segment-btn:hover {
  color: var(--text-main);
}

.segment-btn.active {
  background: var(--color-primary);
  color: #FFFFFF;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.08), 0 1px 2px rgba(0, 0, 0, 0.04);
}

/* Sub-selector de subtema */
.subtopics-scroll {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  padding-bottom: 12px;
  margin-bottom: 20px;
  scrollbar-width: none;
}
.subtopics-scroll::-webkit-scrollbar {
  display: none;
}

.subtopic-chip {
  padding: 6px 14px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.7);
  border: none;
  font-size: 0.82rem;
  font-weight: 500;
  color: var(--text-secondary);
  cursor: pointer;
  box-shadow: var(--shadow-subtle);
  transition: var(--transition-smooth);
  white-space: nowrap;
}

.subtopic-chip:hover {
  background: #FFFFFF;
  color: var(--text-main);
}

.subtopic-chip.active {
  background: var(--color-primary);
  color: #FFFFFF;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.06);
}

/* Tarjeta Principal del Ejercicio */
.exercise-card {
  background: var(--card-bg);
  backdrop-filter: blur(24px);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-card);
  padding: clamp(20px, 4vw, 36px);
  margin-bottom: 24px;
  transition: var(--transition-smooth);
  position: relative;
  overflow: hidden;
}

.exercise-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 18px;
  flex-wrap: wrap;
  gap: 10px;
}

.exercise-tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-primary);
  background: var(--color-primary-light);
  padding: 5px 12px;
  border-radius: 999px;
}

.indeterminate-badge {
  background: #FFF0F5;
  color: #AF125A;
  font-size: 0.76rem;
  font-weight: 700;
  padding: 4px 10px;
  border-radius: 999px;
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

.exercise-prompt-box {
  background: #FFFFFF;
  border-radius: var(--radius-lg);
  padding: 24px 20px;
  box-shadow: var(--shadow-subtle);
  margin-bottom: 24px;
  text-align: center;
}

.exercise-math-display {
  font-size: clamp(1.2rem, 3vw, 1.6rem);
  padding: 12px 0;
  color: var(--text-main);
  overflow-x: auto;
  overflow-y: hidden;
}

/* Grid de Opciones de Selección Múltiple */
.options-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 14px;
  margin-bottom: 24px;
}

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

.option-btn {
  background: #FFFFFF;
  border: none;
  border-radius: var(--radius-lg);
  padding: 18px 20px;
  font-size: 1.12rem;
  color: var(--text-main);
  box-shadow: var(--shadow-subtle);
  cursor: pointer;
  transition: var(--transition-smooth);
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 64px;
  text-align: center;
  position: relative;
  user-select: none;
}

.option-btn:hover:not(:disabled) {
  transform: translateY(-2px);
  box-shadow: var(--shadow-hover);
  background: #FFFFFF;
}

.option-btn:active:not(:disabled) {
  transform: scale(0.98);
}

/* ESTADO SELECCIONADO PRELIMINAR (Requisito: #AF125A) */
.option-btn.selected {
  background: var(--color-primary) !important;
  color: #FFFFFF !important;
  box-shadow: 0 4px 14px rgba(175, 18, 90, 0.25) !important;
  transform: translateY(-2px);
}

.option-btn.selected .katex {
  color: #FFFFFF !important;
}

/* Retroalimentación Visual Post-Confirmación */
.option-btn.correct-reveal {
  background: var(--color-success) !important;
  color: #FFFFFF !important;
  box-shadow: 0 6px 18px rgba(52, 199, 89, 0.35) !important;
}
.option-btn.correct-reveal .katex {
  color: #FFFFFF !important;
}

.option-btn.wrong-reveal {
  background: var(--color-error) !important;
  color: #FFFFFF !important;
  box-shadow: 0 6px 18px rgba(255, 59, 48, 0.35) !important;
}
.option-btn.wrong-reveal .katex {
  color: #FFFFFF !important;
}

/* Botonera de Acción Apple */
.actions-row {
  display: flex;
  gap: 12px;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
}

.btn-apple {
  border: none;
  border-radius: 999px;
  padding: 12px 24px;
  font-size: 0.94rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition-smooth);
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.btn-hint {
  background: #FFFFFF;
  color: var(--color-primary);
  box-shadow: var(--shadow-subtle);
}

.btn-hint:hover:not(:disabled) {
  background: var(--color-primary-light);
  transform: translateY(-1px);
}

.btn-hint:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* Botón de Acción Principal (Confirmar -> Siguiente) */
.btn-primary-action {
  background: var(--color-primary);
  color: #FFFFFF;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08), 0 1px 2px rgba(0, 0, 0, 0.04);
}

.btn-primary-action:hover:not(:disabled) {
  background: var(--color-primary-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.12);
}

.btn-primary-action:disabled {
  opacity: 0.42;
  cursor: not-allowed;
  transform: none !important;
  box-shadow: none !important;
}

.btn-primary-action.state-next {
  background: #1D1D1F;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.12);
}

.btn-primary-action.state-next:hover {
  background: #000000;
  transform: translateY(-1px);
  box-shadow: 0 4px 14px rgba(0, 0, 0, 0.18);
}

.btn-apple:active:not(:disabled) {
  transform: scale(0.97);
}

/* Panel de Pistas Progresivas */
.hints-container {
  margin-top: 20px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.hint-card {
  background: rgba(255, 255, 255, 0.95);
  border-radius: var(--radius-md);
  padding: 14px 18px;
  box-shadow: var(--shadow-subtle);
  font-size: 0.92rem;
  color: var(--text-main);
  animation: slideDown 0.3s ease-out forwards;
  display: flex;
  gap: 12px;
  align-items: flex-start;
}

.hint-badge {
  font-size: 0.72rem;
  font-weight: 700;
  padding: 3px 8px;
  border-radius: 6px;
  white-space: nowrap;
  background: var(--color-primary-light);
  color: var(--color-primary);
}

.hint-level-1 .hint-badge { background: #E8F4FE; color: #0071E3; }
.hint-level-2 .hint-badge { background: #FFF4E5; color: #D97706; }
.hint-level-3 .hint-badge { background: #FDE8EF; color: #AF125A; }

/* Tarjeta de Recurso de Estudio Recomendado */
.resource-card {
  background: rgba(255, 255, 255, 0.95);
  border-radius: var(--radius-md);
  padding: 14px 18px;
  box-shadow: var(--shadow-subtle);
  display: flex;
  gap: 14px;
  align-items: center;
  animation: slideDown 0.3s ease-out forwards;
  border-left: 3px solid var(--color-primary);
  margin-top: 4px;
}

.resource-icon-box {
  width: 36px;
  height: 36px;
  border-radius: 10px;
  background: var(--color-primary-light);
  color: var(--color-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.resource-content {
  flex: 1;
}

.resource-tagline {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-tertiary);
  margin-bottom: 2px;
}

.resource-anchor {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.92rem;
  font-weight: 600;
  color: var(--color-primary);
  text-decoration: none;
  transition: var(--transition-smooth);
}

.resource-anchor:hover {
  color: var(--color-primary-hover);
  text-decoration: underline;
}

.resource-desc {
  font-size: 0.82rem;
  color: var(--text-secondary);
  margin-top: 2px;
  line-height: 1.4;
}

/* Panel de Solución Paso a Paso */
.solution-panel {
  margin-top: 24px;
  background: #FFFFFF;
  border-radius: var(--radius-lg);
  padding: 22px;
  box-shadow: var(--shadow-card);
  animation: fadeIn 0.35s ease-out forwards;
  display: none;
}

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

.solution-header {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: 14px;
}

.solution-steps {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.solution-step {
  padding: 10px 14px;
  background: rgba(239, 253, 254, 0.5);
  border-radius: var(--radius-md);
  font-size: 0.92rem;
}

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

@keyframes fadeIn {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

/* ==========================================================================
   Mascota Sonora Interactiva (Easter Egg Gracioso)
   ========================================================================== */
.floating-mascot-container {
  position: fixed;
  bottom: 24px;
  right: 24px;
  z-index: 1000;
  display: flex;
  flex-direction: column;
  align-items: flex-end;
}

.mascot-bubble {
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(8px);
  color: var(--color-primary);
  font-size: 0.76rem;
  font-weight: 700;
  padding: 5px 12px;
  border-radius: 999px;
  box-shadow: 0 4px 12px rgba(15, 23, 42, 0.1);
  margin-bottom: 8px;
  white-space: nowrap;
  pointer-events: none;
  transition: all 0.25s ease;
  transform-origin: bottom right;
  opacity: 0.9;
}

.mascot-btn {
  width: 72px;
  height: 72px;
  border-radius: 50%;
  border: 3.5px solid #FFFFFF;
  background: #EFFDFE;
  padding: 0;
  margin: 0;
  cursor: pointer;
  overflow: hidden;
  box-shadow: 0 8px 24px -2px rgba(15, 23, 42, 0.16), 0 3px 8px -1px rgba(15, 23, 42, 0.08);
  transition: transform 0.25s cubic-bezier(0.175, 0.885, 0.32, 1.275), box-shadow 0.25s ease;
  display: flex;
  align-items: center;
  justify-content: center;
}

.mascot-btn:hover {
  transform: scale(1.1) rotate(5deg);
  box-shadow: 0 12px 30px -3px rgba(175, 18, 90, 0.28), 0 4px 12px rgba(0, 0, 0, 0.12);
}

.mascot-btn:active {
  transform: scale(0.92) rotate(-5deg);
}

.mascot-btn.animating {
  animation: mascotBounce 0.55s cubic-bezier(0.36, 0.07, 0.19, 0.97);
}

.mascot-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center;
  display: block;
  user-select: none;
  -webkit-user-drag: none;
}

@keyframes mascotBounce {
  0% { transform: scale(1) rotate(0deg); }
  20% { transform: scale(1.3, 0.72) rotate(-12deg); }
  40% { transform: scale(0.78, 1.28) rotate(14deg); }
  65% { transform: scale(1.15, 0.9) rotate(-6deg); }
  85% { transform: scale(0.95, 1.05) rotate(3deg); }
  100% { transform: scale(1) rotate(0deg); }
}

/* ==========================================================================
   Optimizaciones Específicas Mobile-First (Resoluciones <= 640px)
   ========================================================================== */
@media (max-width: 640px) {
  .app-container {
    padding: 16px 12px;
  }
  
  .app-header {
    margin-bottom: 18px;
  }

  .stats-bar {
    gap: 6px;
    margin-top: 12px;
  }

  .stat-pill {
    padding: 6px 12px;
    font-size: 0.8rem;
  }

  .exercise-card {
    padding: 18px 14px;
    border-radius: 18px;
  }

  .exercise-header {
    margin-bottom: 12px;
  }

  .exercise-prompt-box {
    padding: 16px 10px;
    margin-bottom: 18px;
  }

  .exercise-math-display {
    font-size: 1.25rem;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    padding-bottom: 6px;
  }

  .options-grid {
    grid-template-columns: 1fr;
    gap: 10px;
    margin-bottom: 18px;
  }

  .option-btn {
    min-height: 56px;
    padding: 14px 16px;
    font-size: 1.05rem;
  }

  .actions-row {
    flex-direction: column;
    width: 100%;
    gap: 10px;
  }

  .btn-apple {
    width: 100%;
    justify-content: center;
    padding: 14px 18px;
    font-size: 0.98rem;
  }

  /* Pistas Responsivas (Disposición Vertical para evitar compresión) */
  .hint-card {
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
    padding: 14px 14px;
  }

  .hint-badge {
    align-self: flex-start;
    font-size: 0.72rem;
    padding: 4px 10px;
  }

  .hint-content {
    width: 100%;
    font-size: 0.92rem;
    line-height: 1.5;
    word-break: break-word;
    overflow-wrap: break-word;
  }

  /* Recurso de Estudio Responsivo */
  .resource-card {
    flex-direction: column;
    align-items: flex-start;
    gap: 10px;
    padding: 14px 14px;
  }

  .resource-icon-box {
    width: 32px;
    height: 32px;
  }

  .resource-content {
    width: 100%;
    word-break: break-word;
    overflow-wrap: break-word;
  }

  .resource-anchor {
    font-size: 0.88rem;
    line-height: 1.35;
  }

  .resource-desc {
    font-size: 0.82rem;
    line-height: 1.45;
  }

  /* Solución paso a paso en mobile */
  .solution-panel {
    padding: 16px 14px;
  }

  .solution-step {
    padding: 10px 12px;
    font-size: 0.88rem;
    line-height: 1.45;
    word-break: break-word;
    overflow-wrap: break-word;
  }

  /* Mascota flotante compacta en mobile */
  .floating-mascot-container {
    bottom: 16px;
    right: 16px;
  }

  .mascot-btn {
    width: 56px;
    height: 56px;
    border-width: 2.5px;
  }

  .mascot-bubble {
    font-size: 0.72rem;
    padding: 3px 8px;
  }
}

/* Accesibilidad y Preferencia de Movimiento Reducido */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}