/* ========== VARIABLES ========== */
:root {
  --primary: #6c5ce7;
  --primary-dark: #5a4bd1;
  --secondary: #00cec9;
  --accent: #fd79a8;
  --warning: #fdcb6e;
  --success: #00b894;
  --danger: #e74c3c;
  --bg: #f8f9ff;
  --card-bg: #ffffff;
  --text: #2d3436;
  --text-light: #636e72;
  --border: #dfe6e9;
  --shadow: 0 4px 15px rgba(0,0,0,0.08);
  --shadow-lg: 0 8px 30px rgba(0,0,0,0.12);
  --radius: 16px;
  --radius-sm: 10px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ========== RESET ========== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Fredoka', sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  overflow-x: hidden;
  -webkit-tap-highlight-color: transparent;
}

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

/* ========== HEADER ========== */
.app-header {
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: white;
  padding: 12px 20px;
  box-shadow: var(--shadow);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-content {
  max-width: 1400px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  flex-wrap: wrap;
}

.logo {
  font-size: 1.6rem;
  font-weight: 700;
  text-shadow: 2px 2px 0 rgba(0,0,0,0.1);
  white-space: nowrap;
}

.progress-bar-container {
  display: flex;
  align-items: center;
  gap: 10px;
  min-width: 200px;
}

.progress-bar-track {
  flex: 1;
  height: 12px;
  background: rgba(255,255,255,0.3);
  border-radius: 6px;
  overflow: hidden;
}

.progress-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--warning), #ffeaa7);
  border-radius: 6px;
  width: 0%;
  transition: width 0.5s ease;
  box-shadow: 0 0 10px rgba(255,255,255,0.5);
}

.progress-text {
  font-size: 0.85rem;
  font-weight: 600;
  white-space: nowrap;
}

/* ========== LAYOUT ========== */
.app-layout {
  display: grid;
  grid-template-columns: 400px 1fr;
  max-width: 1400px;
  margin: 0 auto;
  gap: 0;
  min-height: calc(100vh - 70px);
}

/* ========== CUBE VIEWER ========== */
.cube-viewer {
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  background: white;
  border-right: 1px solid var(--border);
  position: sticky;
  top: 70px;
  height: calc(100vh - 70px);
  overflow-y: auto;
}

#cube-canvas-container {
  width: 100%;
  aspect-ratio: 1;
  border-radius: var(--radius);
  background: linear-gradient(135deg, #a8c0ff, #fce38a);
  overflow: hidden;
  position: relative;
  cursor: grab;
  min-height: 250px;
  flex-shrink: 0;
}

#cube-canvas-container:active {
  cursor: grabbing;
}

#cube-canvas-container canvas {
  display: block;
}

/* Speed control */
.speed-control {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.9rem;
  color: var(--text-light);
}

.speed-control input[type="range"] {
  flex: 1;
  accent-color: var(--primary);
  height: 6px;
}

/* Quick actions */
.cube-quick-actions {
  display: flex;
  gap: 8px;
}

.cube-quick-actions .btn {
  flex: 1;
}

/* Current move display */
.current-move-display {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 14px;
  background: var(--primary);
  color: white;
  border-radius: var(--radius-sm);
  animation: pulse 1s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.02); }
}

.current-move-label {
  font-size: 0.9rem;
}

.current-move-chip {
  font-size: 1.3rem;
  font-weight: 700;
  background: white;
  color: var(--primary);
  padding: 2px 12px;
  border-radius: 8px;
}

/* Move history */
.move-history-container {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  min-height: 40px;
}

.move-history-label {
  font-size: 0.85rem;
  color: var(--text-light);
  white-space: nowrap;
  padding-top: 4px;
}

.move-history {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
}

.move-history .move-chip {
  font-size: 0.75rem;
  padding: 2px 8px;
  border-radius: 6px;
  font-weight: 600;
  color: white;
}

/* ========== BUTTONS ========== */
.btn {
  padding: 10px 18px;
  border-radius: var(--radius-sm);
  font-size: 1rem;
  font-weight: 600;
  transition: var(--transition);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  text-decoration: none;
  user-select: none;
}

.btn:active {
  transform: scale(0.95);
}

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

.btn-secondary {
  background: var(--border);
  color: var(--text);
}
.btn-secondary:hover { background: #b2bec3; }

.btn-complete {
  background: var(--success);
  color: white;
}
.btn-complete:hover { background: #00a381; }

.btn-complete.completed {
  background: var(--success);
  opacity: 0.6;
  cursor: default;
}

.btn-scramble {
  background: var(--accent);
  color: white;
}
.btn-scramble:hover { background: #e84393; }

.btn-reset {
  background: var(--border);
  color: var(--text);
}
.btn-reset:hover { background: #b2bec3; }

.btn-undo {
  background: var(--warning);
  color: var(--text);
}
.btn-undo:hover { background: #e1b956; }

.btn-large {
  padding: 14px 24px;
  font-size: 1.1rem;
}

.btn-video {
  background: #e74c3c;
  color: white;
  margin-top: 8px;
}
.btn-video:hover { background: #c0392b; }

.btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

/* ========== CONTENT AREA ========== */
.content-area {
  padding: 20px;
  max-width: 100%;
}

/* Tabs */
.tabs {
  display: flex;
  gap: 4px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}

.tab {
  padding: 10px 18px;
  border-radius: var(--radius-sm);
  font-size: 1rem;
  font-weight: 600;
  background: transparent;
  color: var(--text-light);
  transition: var(--transition);
}

.tab:hover {
  background: var(--border);
  color: var(--text);
}

.tab.active {
  background: var(--primary);
  color: white;
  box-shadow: var(--shadow);
}

/* Tab content */
.tab-content {
  display: none;
  animation: fadeIn 0.3s ease;
}

.tab-content.active {
  display: block;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

.tab-content h2 {
  font-size: 1.8rem;
  margin-bottom: 8px;
  color: var(--text);
}

.tab-intro {
  font-size: 1.05rem;
  color: var(--text-light);
  margin-bottom: 20px;
}

/* ========== LEARN MODE ========== */
.learn-header {
  margin-bottom: 16px;
}

.learn-header h2 {
  margin-bottom: 4px;
}

.learn-subtitle {
  color: var(--text-light);
  font-size: 1rem;
}

/* Step dots */
.step-dots {
  display: flex;
  gap: 8px;
  justify-content: center;
  margin-bottom: 20px;
  flex-wrap: wrap;
}

.step-dot {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 3px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.1rem;
  cursor: pointer;
  transition: var(--transition);
  background: white;
  color: var(--text-light);
}

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

.step-dot.active {
  border-color: var(--primary);
  background: var(--primary);
  color: white;
  transform: scale(1.15);
}

.step-dot.completed {
  border-color: var(--success);
  background: var(--success);
  color: white;
}

.step-dot.completed::after {
  content: '⭐';
  font-size: 0.9rem;
}

.step-dot.completed .dot-num {
  display: none;
}

/* Step content card */
.step-content {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
  margin-bottom: 16px;
}

.step-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
}

.step-icon {
  font-size: 2.5rem;
  line-height: 1;
}

.step-number {
  font-size: 0.85rem;
  color: var(--text-light);
  font-weight: 600;
}

.step-title {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text);
  line-height: 1.2;
}

.step-intro {
  font-size: 1.1rem;
  color: var(--text);
  margin-bottom: 16px;
  padding: 12px 16px;
  background: color-mix(in srgb, var(--step-color, var(--primary)) 10%, white);
  border-radius: var(--radius-sm);
  border-left: 4px solid var(--step-color, var(--primary));
}

.step-instructions {
  list-style: none;
  margin-bottom: 16px;
}

.step-instructions li {
  padding: 10px 0 10px 32px;
  position: relative;
  font-size: 1rem;
  color: var(--text);
  border-bottom: 1px solid var(--border);
}

.step-instructions li:last-child {
  border-bottom: none;
}

.step-instructions li::before {
  content: counter(step-counter);
  counter-increment: step-counter;
  position: absolute;
  left: 0;
  top: 10px;
  width: 24px;
  height: 24px;
  background: var(--step-color, var(--primary));
  color: white;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8rem;
  font-weight: 700;
}

.step-instructions {
  counter-reset: step-counter;
}

/* Algorithm display */
.algorithm-section {
  margin-top: 20px;
}

.algorithm-title {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 10px;
  color: var(--text);
}

.algorithm-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 16px;
}

.algo-chip {
  width: 56px;
  height: 56px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.3rem;
  font-weight: 700;
  color: white;
  transition: var(--transition);
  position: relative;
}

.algo-chip.prime {
  border: 3px solid rgba(255,255,255,0.5);
}

.algo-chip.double::after {
  content: '2';
  position: absolute;
  top: -2px;
  right: 2px;
  font-size: 0.7rem;
  background: white;
  color: var(--text);
  border-radius: 4px;
  padding: 0 4px;
}

.algo-chip.playing {
  transform: scale(1.2);
  box-shadow: 0 0 20px rgba(108,92,231,0.6);
  z-index: 5;
}

.algo-chip.done {
  opacity: 0.5;
}

/* Algorithm buttons */
.algorithm-buttons {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 12px;
}

.step-tip {
  padding: 12px 16px;
  background: #fff9e6;
  border-radius: var(--radius-sm);
  border-left: 4px solid var(--warning);
  font-size: 0.95rem;
  color: var(--text);
  margin-top: 16px;
}

/* Step navigation */
.step-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

/* ========== PRACTICE MODE ========== */
.practice-stats {
  display: flex;
  gap: 12px;
  margin-bottom: 20px;
}

.stat-card {
  flex: 1;
  background: var(--card-bg);
  border-radius: var(--radius-sm);
  padding: 16px;
  text-align: center;
  box-shadow: var(--shadow);
}

.stat-value {
  display: block;
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--primary);
}

.stat-label {
  display: block;
  font-size: 0.85rem;
  color: var(--text-light);
  margin-top: 4px;
}

.practice-actions {
  display: flex;
  gap: 10px;
  margin-bottom: 24px;
  flex-wrap: wrap;
}

.practice-actions .btn {
  flex: 1;
  min-width: 140px;
}

/* Move buttons grid */
.move-buttons-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
}

.move-face-group {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 12px;
  box-shadow: var(--shadow);
}

.move-face-group h4 {
  font-size: 0.9rem;
  text-align: center;
  margin-bottom: 8px;
  color: var(--text-light);
  text-transform: uppercase;
  letter-spacing: 1px;
}

.move-face-buttons {
  display: flex;
  gap: 6px;
  justify-content: center;
}

.move-btn {
  width: 52px;
  height: 52px;
  border-radius: 10px;
  font-size: 1.1rem;
  font-weight: 700;
  color: white;
  transition: var(--transition);
  position: relative;
}

.move-btn:active {
  transform: scale(0.9);
}

.move-btn.prime {
  border: 3px solid rgba(255,255,255,0.4);
}

.move-btn.double::after {
  content: '2';
  position: absolute;
  top: -2px;
  right: 2px;
  font-size: 0.65rem;
  background: white;
  color: var(--text);
  border-radius: 4px;
  padding: 0 4px;
  font-weight: 700;
}

/* ========== MOVE GUIDE ========== */
.move-guide-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  gap: 12px;
  margin-bottom: 24px;
}

.move-guide-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 20px;
  text-align: center;
  box-shadow: var(--shadow);
  border-top: 5px solid var(--card-color);
  transition: var(--transition);
}

.move-guide-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.move-guide-letter {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--card-color);
  margin-bottom: 4px;
}

.move-guide-name {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 8px;
}

.move-guide-card p {
  font-size: 0.9rem;
  color: var(--text-light);
}

.move-guide-extra {
  margin-bottom: 20px;
}

.move-guide-symbols {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 12px;
}

.symbol-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
  display: flex;
  gap: 16px;
  align-items: flex-start;
}

.symbol-icon {
  font-size: 2rem;
  color: var(--primary);
  flex-shrink: 0;
}

.symbol-text strong {
  display: block;
  font-size: 1.1rem;
  margin-bottom: 4px;
}

.symbol-text p {
  font-size: 0.95rem;
  color: var(--text-light);
}

.symbol-text .example {
  margin-top: 6px;
  color: var(--primary);
  font-weight: 600;
}

.move-guide-tip {
  background: #fff9e6;
  border-radius: var(--radius);
  padding: 16px 20px;
  border-left: 4px solid var(--warning);
}

/* ========== TIPS ========== */
.tips-list {
  display: grid;
  gap: 12px;
}

.tip-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
  display: flex;
  gap: 16px;
  align-items: flex-start;
  transition: var(--transition);
}

.tip-card:hover {
  transform: translateX(4px);
}

.tip-icon {
  font-size: 2.5rem;
  flex-shrink: 0;
  line-height: 1;
}

.tip-body h3 {
  font-size: 1.15rem;
  margin-bottom: 6px;
}

.tip-body p {
  font-size: 0.95rem;
  color: var(--text-light);
}

.move-sayings {
  list-style: none;
  margin-top: 8px;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4px;
}

.move-sayings li {
  padding: 4px 0;
  font-size: 0.9rem;
}

/* ========== VIDEOS ========== */
.video-cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 20px;
}

.video-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: var(--transition);
}

.video-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
}

.video-thumbnail {
  height: 160px;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
}

.video-play {
  font-size: 3rem;
  color: white;
  text-shadow: 0 4px 10px rgba(0,0,0,0.3);
}

.video-badge {
  position: absolute;
  top: 10px;
  left: 10px;
  background: rgba(0,0,0,0.5);
  color: white;
  padding: 4px 10px;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 600;
}

.video-info {
  padding: 16px;
}

.video-info h3 {
  font-size: 1.1rem;
  margin-bottom: 8px;
}

.video-info p {
  font-size: 0.9rem;
  color: var(--text-light);
  margin-bottom: 8px;
}

/* ========== CELEBRATION ========== */
.celebration {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,0.7);
  z-index: 1000;
  justify-content: center;
  align-items: center;
}

.celebration.show {
  display: flex;
}

.celebration-content {
  background: white;
  border-radius: 24px;
  padding: 40px;
  text-align: center;
  z-index: 10;
  max-width: 400px;
  animation: bounceIn 0.5s ease;
}

@keyframes bounceIn {
  0% { transform: scale(0.3); opacity: 0; }
  50% { transform: scale(1.05); }
  100% { transform: scale(1); opacity: 1; }
}

.celebration-content h2 {
  font-size: 2rem;
  margin-bottom: 12px;
}

.celebration-subtitle {
  font-size: 1.3rem;
  margin: 12px 0 20px;
  color: var(--primary);
}

.confetti {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  overflow: hidden;
}

.confetti-piece {
  position: absolute;
  width: 10px;
  height: 10px;
  top: -20px;
  animation: confettiFall linear forwards;
}

@keyframes confettiFall {
  to {
    transform: translateY(100vh) rotate(720deg);
  }
}

/* ========== LOADING ========== */
.loading {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: var(--bg);
  z-index: 9999;
  display: flex;
  justify-content: center;
  align-items: center;
  transition: opacity 0.5s ease;
}

.loading.hidden {
  opacity: 0;
  pointer-events: none;
}

.loading-content {
  text-align: center;
}

.loading-cube {
  font-size: 4rem;
  animation: spin 2s linear infinite;
  display: inline-block;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

.loading-content p {
  margin-top: 16px;
  font-size: 1.2rem;
  color: var(--text-light);
}

/* ========== TOAST ========== */
.toast {
  position: fixed;
  bottom: 30px;
  left: 50%;
  transform: translateX(-50%) translateY(100px);
  background: var(--primary);
  color: white;
  padding: 14px 28px;
  border-radius: 30px;
  font-size: 1.1rem;
  font-weight: 600;
  box-shadow: var(--shadow-lg);
  z-index: 500;
  opacity: 0;
  transition: all 0.3s ease;
  pointer-events: none;
  white-space: nowrap;
}

.toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* ========== RESPONSIVE ========== */
@media (max-width: 900px) {
  .app-layout {
    grid-template-columns: 1fr;
  }

  .cube-viewer {
    position: relative;
    top: 0;
    height: auto;
    border-right: none;
    border-bottom: 1px solid var(--border);
  }

  #cube-canvas-container {
    max-height: 300px;
  }

  .header-content {
    justify-content: center;
  }

  .progress-bar-container {
    width: 100%;
    max-width: 300px;
  }

  .move-buttons-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .practice-stats {
    flex-direction: row;
  }

  .step-nav {
    justify-content: center;
  }
}

@media (max-width: 500px) {
  .logo {
    font-size: 1.3rem;
  }

  .tab {
    padding: 8px 12px;
    font-size: 0.9rem;
  }

  .step-content {
    padding: 16px;
  }

  .move-buttons-grid {
    grid-template-columns: 1fr;
  }

  .move-sayings {
    grid-template-columns: 1fr;
  }

  .practice-actions .btn {
    min-width: 100%;
  }
}