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

html, body {
  height: 100%;
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background: #0a0a1a;
  color: #e0e0e0;
  overflow: hidden;
  -webkit-user-select: none;
  user-select: none;
}

#app {
  display: flex;
  flex-direction: column;
  height: 100vh;
}

/* ===== HEADER ===== */
#header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 28px;
  background: rgba(10, 10, 26, 0.9);
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
  flex-shrink: 0;
}

#logo {
  display: flex;
  align-items: center;
  gap: 12px;
}

#logo h1 {
  font-size: 18px;
  font-weight: 600;
  background: linear-gradient(135deg, #06d6a0, #a855f7);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -0.3px;
}

#badge {
  font-size: 11px;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 20px;
  background: rgba(168, 85, 247, 0.15);
  color: #a855f7;
  border: 1px solid rgba(168, 85, 247, 0.3);
  letter-spacing: 0.5px;
}

/* ===== VISUALIZER ===== */
#visualizer {
  flex: 1;
  display: flex;
  align-items: flex-end;
  justify-content: center;
  padding: 32px 24px 16px;
  position: relative;
  background: 
    radial-gradient(ellipse at 50% 100%, rgba(6, 214, 160, 0.04) 0%, transparent 60%),
    radial-gradient(ellipse at 20% 20%, rgba(168, 85, 247, 0.03) 0%, transparent 50%),
    linear-gradient(180deg, #0a0a1a 0%, #0f0f23 100%);
}

#bars-container {
  display: flex;
  align-items: flex-end;
  justify-content: center;
  gap: 3px;
  position: absolute;
  bottom: 16px;
  left: 24px;
  right: 24px;
  top: 32px;
  max-width: 1200px;
  margin: 0 auto;
}

.bar {
  flex: 1;
  min-width: 4px;
  max-width: 40px;
  border-radius: 4px 4px 0 0;
  transition: height 0.12s ease-out, background 0.15s ease, box-shadow 0.15s ease;
  position: relative;
  background: linear-gradient(180deg, #667eea 0%, #3b4cb8 100%);
  box-shadow: 0 0 8px rgba(102, 126, 234, 0.2);
}

/* Bar States */
.bar.comparing {
  background: linear-gradient(180deg, #22d3ee 0%, #0891b2 100%);
  box-shadow: 0 0 18px rgba(34, 211, 238, 0.5), 0 0 40px rgba(34, 211, 238, 0.15);
}

.bar.swapping {
  background: linear-gradient(180deg, #fb7185 0%, #e11d48 100%);
  box-shadow: 0 0 18px rgba(251, 113, 133, 0.5), 0 0 40px rgba(251, 113, 133, 0.15);
}

.bar.pivot {
  background: linear-gradient(180deg, #fbbf24 0%, #d97706 100%);
  box-shadow: 0 0 18px rgba(251, 191, 36, 0.5), 0 0 40px rgba(251, 191, 36, 0.15);
}

.bar.sorted {
  background: linear-gradient(180deg, #34d399 0%, #059669 100%);
  box-shadow: 0 0 12px rgba(52, 211, 153, 0.35), 0 0 30px rgba(52, 211, 153, 0.1);
}

/* Hover shimmer on bars */
.bar::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 40%;
  background: linear-gradient(180deg, rgba(255,255,255,0.12) 0%, transparent 100%);
  border-radius: 4px 4px 0 0;
  pointer-events: none;
}

/* ===== LOADING OVERLAY ===== */
#loading-overlay {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 16px;
  background: rgba(10, 10, 26, 0.92);
  backdrop-filter: blur(8px);
  z-index: 10;
  transition: opacity 0.5s ease;
}

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

#loading-overlay p {
  font-size: 14px;
  color: rgba(255, 255, 255, 0.5);
  font-weight: 500;
  letter-spacing: 0.3px;
}

.spinner {
  width: 36px;
  height: 36px;
  border: 3px solid rgba(168, 85, 247, 0.2);
  border-top-color: #a855f7;
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

/* ===== CONTROLS ===== */
#controls {
  flex-shrink: 0;
  padding: 16px 24px;
  background: rgba(15, 15, 35, 0.85);
  backdrop-filter: blur(20px);
  border-top: 1px solid rgba(255, 255, 255, 0.06);
}

#controls-inner {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 32px;
  max-width: 1200px;
  margin: 0 auto;
  flex-wrap: wrap;
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.control-label {
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: rgba(255, 255, 255, 0.4);
}

/* Algorithm Buttons */
#algo-buttons, #speed-buttons {
  display: flex;
  gap: 4px;
  flex-wrap: wrap;
}

.algo-btn, .speed-btn {
  padding: 8px 14px;
  border: 1px solid rgba(255, 255, 255, 0.1);
  background: rgba(255, 255, 255, 0.04);
  color: rgba(255, 255, 255, 0.65);
  border-radius: 8px;
  font-size: 13px;
  font-family: 'Inter', sans-serif;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s ease;
}

.algo-btn:hover, .speed-btn:hover {
  background: rgba(255, 255, 255, 0.08);
  color: #fff;
  border-color: rgba(255, 255, 255, 0.2);
}

.algo-btn.active {
  background: linear-gradient(135deg, rgba(168, 85, 247, 0.25), rgba(6, 214, 160, 0.15));
  border-color: rgba(168, 85, 247, 0.5);
  color: #fff;
  box-shadow: 0 0 12px rgba(168, 85, 247, 0.2);
}

.speed-btn.active {
  background: rgba(6, 214, 160, 0.15);
  border-color: rgba(6, 214, 160, 0.4);
  color: #06d6a0;
}

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

/* Size Slider */
#size-slider {
  -webkit-appearance: none;
  appearance: none;
  width: 140px;
  height: 6px;
  border-radius: 3px;
  background: rgba(255, 255, 255, 0.1);
  outline: none;
  cursor: pointer;
}

#size-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: linear-gradient(135deg, #06d6a0, #a855f7);
  cursor: pointer;
  box-shadow: 0 0 10px rgba(6, 214, 160, 0.4);
  transition: box-shadow 0.2s ease;
}

#size-slider::-webkit-slider-thumb:hover {
  box-shadow: 0 0 16px rgba(6, 214, 160, 0.6);
}

#size-slider::-moz-range-thumb {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: linear-gradient(135deg, #06d6a0, #a855f7);
  border: none;
  cursor: pointer;
  box-shadow: 0 0 10px rgba(6, 214, 160, 0.4);
}

#size-slider:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

#size-value {
  color: #06d6a0;
  font-weight: 600;
}

/* Action Buttons */
.actions {
  flex-direction: row !important;
  gap: 10px !important;
  align-items: flex-end;
}

.action-btn {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  border: none;
  border-radius: 10px;
  font-size: 14px;
  font-family: 'Inter', sans-serif;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.25s ease;
}

.generate-btn {
  background: rgba(255, 255, 255, 0.08);
  color: rgba(255, 255, 255, 0.8);
  border: 1px solid rgba(255, 255, 255, 0.12);
}

.generate-btn:hover {
  background: rgba(255, 255, 255, 0.14);
  color: #fff;
  transform: translateY(-1px);
}

.sort-btn {
  background: linear-gradient(135deg, #06d6a0, #059669);
  color: #fff;
  box-shadow: 0 4px 15px rgba(6, 214, 160, 0.3);
}

.sort-btn:hover:not(:disabled) {
  box-shadow: 0 6px 20px rgba(6, 214, 160, 0.45);
  transform: translateY(-1px);
}

.sort-btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
  transform: none;
}

.reverse-btn {
  background: linear-gradient(135deg, #a855f7, #7c3aed);
  color: #fff;
  box-shadow: 0 4px 15px rgba(168, 85, 247, 0.3);
}

.reverse-btn:hover:not(:disabled) {
  box-shadow: 0 6px 20px rgba(168, 85, 247, 0.45);
  transform: translateY(-1px);
}

.reverse-btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
  transform: none;
}

.hidden {
  display: none !important;
}

.action-btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
  transform: none;
}

/* ===== STATS PANEL ===== */
#stats-panel {
  display: flex;
  justify-content: center;
  gap: 32px;
  padding: 10px 24px;
  background: rgba(12, 12, 30, 0.9);
  backdrop-filter: blur(12px);
  border-top: 1px solid rgba(255, 255, 255, 0.06);
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
  flex-shrink: 0;
}

.stat-item {
  display: flex;
  align-items: center;
  gap: 8px;
}

.stat-label {
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  color: rgba(255, 255, 255, 0.4);
}

.stat-value {
  font-size: 13px;
  font-weight: 600;
  font-family: 'Inter', monospace;
  padding: 3px 10px;
  border-radius: 6px;
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid rgba(255, 255, 255, 0.08);
}

#stat-swaps {
  color: #fb7185;
}

#stat-comparisons {
  color: #22d3ee;
}

#stat-time {
  color: #fbbf24;
}

#stat-space {
  color: #a855f7;
}

/* ===== LEGEND ===== */
#legend {
  display: flex;
  justify-content: center;
  gap: 20px;
  padding: 10px 24px;
  background: rgba(10, 10, 26, 0.95);
  border-top: 1px solid rgba(255, 255, 255, 0.04);
  flex-shrink: 0;
}

.legend-item {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 11px;
  color: rgba(255, 255, 255, 0.45);
  font-weight: 500;
}

.legend-dot {
  width: 10px;
  height: 10px;
  border-radius: 3px;
}

.legend-dot.default { background: linear-gradient(135deg, #667eea, #3b4cb8); }
.legend-dot.comparing { background: linear-gradient(135deg, #22d3ee, #0891b2); }
.legend-dot.swapping { background: linear-gradient(135deg, #fb7185, #e11d48); }
.legend-dot.pivot { background: linear-gradient(135deg, #fbbf24, #d97706); }
.legend-dot.sorted { background: linear-gradient(135deg, #34d399, #059669); }

/* ===== RESPONSIVE ===== */
@media (max-width: 1024px) {
  #controls-inner {
    gap: 20px;
  }
  #stats-panel {
    gap: 20px;
  }
}

@media (max-width: 768px) {
  html, body {
    overflow-y: auto;
    overflow-x: hidden;
    height: auto;
    min-height: 100%;
  }
  #app {
    height: auto;
    min-height: 100vh;
  }
  #header {
    padding: 12px 16px;
  }
  #logo h1 {
    font-size: 16px;
  }
  #visualizer {
    padding: 20px 16px 12px;
    min-height: 280px;
  }
  #bars-container {
    left: 16px;
    right: 16px;
    top: 20px;
    bottom: 12px;
  }
  #controls {
    padding: 16px;
  }
  #controls-inner {
    gap: 20px;
    flex-direction: column;
    align-items: stretch;
  }
  .control-group {
    width: 100%;
  }
  #algo-buttons {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 8px;
  }
  #speed-buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 8px;
  }
  .algo-btn, .speed-btn {
    padding: 8px 4px;
    font-size: 12px;
    text-align: center;
  }
  .actions {
    flex-direction: row !important;
    gap: 12px !important;
  }
  .action-btn {
    flex: 1;
    justify-content: center;
    padding: 12px;
  }
  #stats-panel {
    gap: 12px;
    padding: 12px 16px;
    flex-wrap: wrap;
    justify-content: space-between;
  }
  .stat-item {
    flex: 1 1 40%;
    margin-bottom: 4px;
  }
  #size-slider {
    width: 100%;
  }
  #legend {
    padding: 12px 16px;
    gap: 12px;
    flex-wrap: wrap;
    justify-content: center;
  }
  #footer {
    padding: 12px 16px;
  }
}

@media (max-width: 480px) {
  #logo {
    gap: 8px;
  }
  #logo svg {
    width: 22px;
    height: 22px;
  }
  #logo h1 {
    font-size: 14px;
    letter-spacing: -0.5px;
  }
  #badge {
    font-size: 9px;
    padding: 3px 6px;
  }
  #visualizer {
    min-height: 220px;
  }
  .algo-btn, .speed-btn {
    padding: 8px 2px;
    font-size: 11px;
  }
  .stat-label {
    font-size: 10px;
  }
  .stat-value {
    font-size: 11px;
    padding: 2px 6px;
  }
  .action-btn {
    font-size: 12px;
    padding: 10px 8px;
    gap: 4px;
  }
  .action-btn svg {
    width: 14px;
    height: 14px;
  }
  .legend-item {
    font-size: 10px;
    gap: 4px;
  }
}

/* ===== ANIMATION FOR COMPLETED SORT ===== */
@keyframes celebrate {
  0%, 100% { transform: scaleY(1); }
  50% { transform: scaleY(1.08); }
}

.bar.celebrate {
  animation: celebrate 0.4s ease-in-out;
  transform-origin: bottom;
}

/* ===== FOOTER ===== */
#footer {
  text-align: center;
  padding: 12px 24px;
  font-size: 11px;
  color: rgba(255, 255, 255, 0.4);
  background: rgba(10, 10, 26, 0.95);
  border-top: 1px solid rgba(255, 255, 255, 0.04);
  flex-shrink: 0;
}

#footer a {
  color: #06d6a0;
  text-decoration: none;
  transition: color 0.2s;
}

#footer a:hover {
  color: #a855f7;
}