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

:root {
  /* Colors */
  --color-primary: #1D9E75;
  --color-success: #0F6E56;
  --color-warning: #BA7517;
  --color-error: #D85A30;
  --color-bg: #ffffff;
  --color-bg-secondary: #f5f5f5;
  --color-text-primary: #1a1a1a;
  --color-text-secondary: #666666;
  --color-border: #e0e0e0;

  /* Spacing */
  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 16px;
  --spacing-lg: 24px;
  --spacing-xl: 32px;

  /* Typography */
  --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
  --font-size-sm: 12px;
  --font-size-base: 14px;
  --font-size-lg: 16px;
  --font-size-xl: 18px;
  --font-size-xxl: 24px;
  --font-size-3xl: 32px;

  /* Border & Shadow */
  --border-radius: 12px;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.15);

  /* Animation */
  --transition: all 150ms ease-in-out;
}

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

body {
  font-family: var(--font-family);
  background-color: var(--color-bg);
  color: var(--color-text-primary);
  line-height: 1.5;
  -webkit-user-select: none;
  user-select: none;
  -webkit-touch-callout: none;
}

/* Status Bar */
.status-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 8px 16px;
  background-color: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  position: sticky;
  top: 0;
  z-index: 100;
}

.status-left,
.status-right {
  flex: 1;
  display: flex;
  align-items: center;
  gap: 4px;
}

.status-right {
  justify-content: flex-end;
}

.status-center {
  flex: 2;
  text-align: center;
  font-weight: 500;
  font-size: var(--font-size-lg);
}

.status-battery {
  width: 16px;
  height: 10px;
  opacity: 0.7;
}

/* App Container */
#app {
  display: flex;
  flex-direction: column;
  height: 100vh;
  max-width: 768px;
  margin: 0 auto;
  background-color: var(--color-bg);
  overflow: hidden;
}

/* Main Control Panel */
.control-panel {
  flex: 1;
  overflow-y: auto;
  overflow-x: hidden;
  padding: var(--spacing-md);
  display: flex;
  flex-direction: column;
  gap: var(--spacing-lg);
  -webkit-overflow-scrolling: touch;
  scrollbar-width: thin;
}

.control-panel::-webkit-scrollbar {
  width: 4px;
}

.control-panel::-webkit-scrollbar-track {
  background: transparent;
}

.control-panel::-webkit-scrollbar-thumb {
  background: var(--color-border);
  border-radius: 2px;
}

/* Sections */
section {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.bpm-section { order: 1; }
.transport-section { order: 2; }
.input-mode-section { order: 2.5; }
.visualization-section { order: 3; flex: 1; }
.tap-section { order: 4; }
.stats-section { order: 5; }
.session-info { order: 6; }

.section-label {
  font-size: var(--font-size-lg);
  font-weight: 600;
  color: var(--color-text-primary);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.label-small {
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--color-text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.3px;
}

/* BPM Section */
.bpm-section {
  gap: var(--spacing-md);
}

.bpm-controls {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.bpm-display-container {
  flex: 1;
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.bpm-slider {
  flex: 1;
  height: 6px;
  border-radius: 3px;
  background: linear-gradient(to right, var(--color-border), var(--color-primary));
  outline: none;
  -webkit-appearance: none;
  appearance: none;
  cursor: pointer;
}

.bpm-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--color-primary);
  cursor: pointer;
  box-shadow: var(--shadow-sm);
  transition: transform 150ms ease;
}

.bpm-slider::-webkit-slider-thumb:active {
  transform: scale(1.2);
}

.bpm-slider::-moz-range-thumb {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--color-primary);
  border: none;
  cursor: pointer;
  box-shadow: var(--shadow-sm);
  transition: transform 150ms ease;
}

.bpm-slider::-moz-range-thumb:active {
  transform: scale(1.2);
}

.bpm-display {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  min-width: 60px;
  text-align: center;
}

.bpm-value {
  font-size: var(--font-size-3xl);
  font-weight: 700;
  color: var(--color-primary);
}

.bpm-unit {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  font-weight: 600;
}

.time-signature-controls {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.select-small {
  flex: 1;
  padding: 8px 12px;
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius);
  font-size: var(--font-size-base);
  background-color: var(--color-bg-secondary);
  color: var(--color-text-primary);
  cursor: pointer;
  outline: none;
  transition: var(--transition);
}

.select-small:focus {
  border-color: var(--color-primary);
  background-color: var(--color-bg);
}

/* Buttons */
.btn-primary,
.btn-secondary,
.btn-small {
  border: none;
  border-radius: var(--border-radius);
  font-family: var(--font-family);
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  -webkit-tap-highlight-color: transparent;
  outline: none;
}

.btn-primary {
  background-color: var(--color-primary);
  color: white;
  padding: var(--spacing-md) var(--spacing-lg);
  font-size: var(--font-size-lg);
}

.btn-primary:hover:not(:disabled) {
  background-color: var(--color-success);
  box-shadow: var(--shadow-md);
}

.btn-primary:active:not(:disabled) {
  transform: scale(0.95);
}

.btn-primary:disabled {
  background-color: var(--color-border);
  color: var(--color-text-secondary);
  cursor: not-allowed;
  opacity: 0.6;
}

.btn-secondary {
  background-color: var(--color-bg-secondary);
  color: var(--color-text-primary);
  border: 1px solid var(--color-border);
  padding: 10px 16px;
  font-size: var(--font-size-base);
}

.btn-secondary:hover:not(:disabled) {
  background-color: var(--color-border);
  border-color: var(--color-text-secondary);
}

.btn-secondary:active:not(:disabled) {
  transform: scale(0.95);
}

.btn-small {
  width: 44px;
  height: 44px;
  padding: 0;
  background-color: var(--color-bg-secondary);
  color: var(--color-text-primary);
  border: 1px solid var(--color-border);
  font-size: var(--font-size-xl);
}

.btn-small:hover:not(:disabled) {
  background-color: var(--color-border);
}

.btn-small:active:not(:disabled) {
  transform: scale(0.9);
}

/* Transport Controls */
.transport-section {
  flex-direction: row;
  gap: var(--spacing-sm);
}

.btn-transport {
  flex: 1;
  padding: var(--spacing-md) var(--spacing-sm);
  font-size: var(--font-size-base);
  flex-direction: column;
  min-height: 60px;
}

.btn-transport svg {
  width: 24px;
  height: 24px;
}

/* Input Mode Toggle */
.input-mode-section {
  gap: var(--spacing-md);
}

.mode-toggle {
  display: flex;
  gap: var(--spacing-sm);
  background-color: var(--color-bg-secondary);
  border-radius: var(--border-radius);
  padding: 4px;
}

.mode-btn {
  flex: 1;
  padding: 8px 12px;
  border: none;
  border-radius: 8px;
  background-color: transparent;
  color: var(--color-text-secondary);
  font-weight: 600;
  font-size: var(--font-size-sm);
  cursor: pointer;
  transition: var(--transition);
  outline: none;
}

.mode-btn:hover {
  color: var(--color-text-primary);
}

.mode-btn-active {
  background-color: var(--color-primary);
  color: white;
}

/* Instrument Settings */
.instrument-settings {
  background-color: var(--color-bg-secondary);
  border-left: 4px solid var(--color-primary);
  padding: var(--spacing-md);
  border-radius: var(--border-radius);
  gap: var(--spacing-md);
}

/* Tap Section */
.tap-section {
  align-items: center;
  justify-content: center;
  padding: var(--spacing-md) 0;
  order: 4; /* Position after beat grid */
}

.tap-button {
  position: relative;
  width: 100%;
  max-width: 280px;
  aspect-ratio: 1;
  border: none;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-success) 100%);
  color: white;
  font-size: var(--font-size-xxl);
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: var(--shadow-md);
  display: flex;
  align-items: center;
  justify-content: center;
  -webkit-tap-highlight-color: transparent;
  outline: none;
  overflow: hidden;
}

.tap-button:hover:not(:disabled) {
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.2);
}

.tap-button:active:not(:disabled) {
  transform: scale(0.96);
}

.tap-button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.tap-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--spacing-sm);
  pointer-events: none;
}

.tap-icon {
  width: 48px;
  height: 48px;
}

.tap-text {
  font-size: var(--font-size-lg);
  letter-spacing: 1px;
}

.tap-feedback {
  position: absolute;
  width: 100%;
  height: 100%;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(255, 255, 255, 0.5) 0%, transparent 70%);
  opacity: 0;
  animation: tapPulse 0.6s ease-out;
}

@keyframes tapPulse {
  0% {
    opacity: 1;
    transform: scale(0.8);
  }
  100% {
    opacity: 0;
    transform: scale(1.3);
  }
}

.tap-feedback.active {
  animation: tapPulse 0.6s ease-out;
}

/* Visualization Section (PROMINENT) */
.visualization-section {
  gap: var(--spacing-md);
  flex: 1;
  order: 3; /* Position before tap button */
}

.section-label {
  font-size: var(--font-size-xl);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: var(--spacing-sm);
}

.canvas-container {
  background: linear-gradient(to bottom, #f9f9f9, #ffffff);
  border: 2px solid var(--color-border);
  border-radius: var(--border-radius);
  padding: var(--spacing-md);
  overflow-x: auto;
  overflow-y: hidden;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  -webkit-overflow-scrolling: touch;
  flex: 1;
  display: flex;
  align-items: center;
  min-height: 260px;
}

canvas {
  display: block;
  width: 100%;
  height: 240px;
  max-width: 100%;
  cursor: grab;
}

canvas:active {
  cursor: grabbing;
}

/* Stats Section */
.stats-section {
  gap: var(--spacing-md);
}

.stats-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--spacing-md);
}

.stat-item {
  background-color: var(--color-bg-secondary);
  border-radius: var(--border-radius);
  padding: var(--spacing-md);
  text-align: center;
  display: flex;
  flex-direction: column;
  gap: 4px;
  transition: transform 150ms ease;
}

.stat-item.updated {
  animation: statBounce 0.3s ease;
}

@keyframes statBounce {
  0%, 100% {
    transform: scale(1);
  }
  50% {
    transform: scale(1.05);
  }
}

.stat-label {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.3px;
  font-weight: 600;
}

.stat-value {
  font-size: var(--font-size-3xl);
  font-weight: 700;
  color: var(--color-primary);
  line-height: 1;
}

.stat-unit {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
}

/* Session Info */
.session-info {
  background-color: var(--color-bg-secondary);
  border-radius: var(--border-radius);
  padding: var(--spacing-md);
  gap: var(--spacing-sm);
  border: 1px solid var(--color-border);
}

.info-item {
  display: flex;
  justify-content: space-between;
  font-size: var(--font-size-sm);
}

.info-label {
  color: var(--color-text-secondary);
  font-weight: 600;
}

.info-value {
  color: var(--color-text-primary);
  font-weight: 600;
  font-family: 'SF Mono', Monaco, 'Cascadia Code', monospace;
}

/* Tablet & Desktop */
@media (min-width: 768px) {
  .stats-grid {
    grid-template-columns: 1fr 1fr 1fr 1fr;
  }

  .tap-button {
    max-width: 200px;
  }

  .control-panel {
    padding: var(--spacing-xl);
  }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #1a1a1a;
    --color-bg-secondary: #2a2a2a;
    --color-text-primary: #ffffff;
    --color-text-secondary: #a0a0a0;
    --color-border: #404040;
  }
}

/* Portrait orientation lock (mobile) */
@media (max-width: 480px) {
  @supports (max-height: 100dvh) {
    #app {
      height: 100dvh;
    }
  }
}