/* ==========================================================================
   COMPREHENSIVE MOBILE-FIRST PIANO TOUR CSS
   Includes: Piano, Guitar, Audio Controls, and Editor Components
   ========================================================================== */

/* ==========================================================================
   1. CSS Custom Properties & Reset
   ========================================================================== */
:root {
  /* Color Palette */
  --color-primary: #297B51;
  --color-secondary: #295570;
  --color-danger: #AF563A;
  --color-info: #295570;
  --color-surface: #04273C;
  --color-text-primary: #FFFFFF;
  --color-text-secondary: #6F91A5;
  --color-border: #6F91A5;
  --color-warning: #AF7A3A;

  /* Extended Color System */
  --color-green-lightest: #76B595;
  --color-green-light: #499770;
  --color-green-medium: #297B51;
  --color-green-dark: #116038;
  --color-green-darkest: #014221;

  --color-blue-lightest: #6F91A5;
  --color-blue-light: #467089;
  --color-blue-medium: #295570;
  --color-blue-dark: #143E58;
  --color-blue-darkest: #04273C;

  --color-gold-lightest: #FFD7A7;
  --color-gold-light: #D8A668;
  --color-gold-medium: #AF7A3A;
  --color-gold-dark: #895718;
  --color-gold-darkest: #5E3401;

  --color-peach-lightest: #FFBCA7;
  --color-peach-light: #D88368;
  --color-peach-medium: #AF563A;
  --color-peach-dark: #893418;
  --color-peach-darkest: #5E1701;

  /* Mobile-First Sizing & Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-xxl: 3rem;

  /* Touch-friendly measurements */
  --touch-target-min: 44px;
  --touch-spacing: 8px;
  --border-radius-sm: 4px;
  --border-radius: 8px;
  --border-radius-lg: 12px;

  /* Typography Scale */
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 2rem;
  --font-size-4xl: 2.5rem;

  /* Layout constraints */
  --max-width-mobile: 100%;
  --max-width-tablet: 768px;
  --max-width-desktop: 1500px;
  --container-padding: 10px;

  --max-width-main: 1200px;

  /* Component heights */
  --header-height-mobile: auto;
  --score-min-height-mobile: 200px;
  --keyboard-min-height-mobile: 120px;
  --controls-min-height-mobile: auto;

  /* Guitar-specific */
  --guitar-fretboard-width: 100%;
  --guitar-fretboard-height: 200px;
  --guitar-string-height: calc(var(--guitar-fretboard-height) / 6);
}

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

/* ==========================================================================
   2. Base Styles (Mobile First)
   ========================================================================== */
html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  -webkit-tap-highlight-color: rgba(0, 0, 0, 0);
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Arial, sans-serif;
  background: linear-gradient(135deg, 
    var(--color-blue-darkest) 0%, 
    var(--color-blue-medium) 50%, 
    var(--color-blue-lightest) 100%);
  color: var(--color-text-primary);
  min-height: 100vh;
  min-height: 100dvh;
  line-height: 1.5;
  overflow-x: hidden;
  touch-action: manipulation;
}

body.no-scroll {
  overflow: hidden;
  position: fixed;
  width: 100%;
}

/* ==========================================================================
   3. Layout Components (Mobile First)
   ========================================================================== */

.piano-app {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  min-height: 100dvh;
  width: 100%;
}

.piano-app__content-area {
  flex: 1;
  display: flex;
  flex-direction: column;
  padding: var(--container-padding);
  gap: var(--spacing-md);
  width: 100%;
  max-width: var(--max-width-mobile);
  margin: 0 auto;
  align-items: center;
}

/* Header */
.piano-app__header {
  text-align: center;
  margin-bottom: var(--spacing-md);
}

.piano-app__header-title {
  font-size: var(--font-size-3xl);
  font-weight: 800;
  margin-bottom: var(--spacing-md);
  background: linear-gradient(135deg, 
    var(--color-green-medium) 0%, 
    var(--color-green-lightest) 50%, 
    #FFFFFF 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1.2;
}

.piano-app__now-playing {
  min-height: var(--touch-target-min);
  font-size: var(--font-size-lg);
  font-weight: 600;
  color: var(--color-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: var(--spacing-sm);
}

/* ==========================================================================
   4. Wrapper Components
   ========================================================================== */
.outer-wrapper,
.controls-footer {
  background: var(--color-blue-darkest);
  flex-grow: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: var(--container-padding);
  gap: var(--spacing-lg);
  width: 100%;
  max-width: var(--max-width-desktop);
  margin: 0 auto;
}

/* ==========================================================================
   5. Control Sections (Mobile Optimized)
   ========================================================================== */

/* Playback Controls */
.playback-controls,
.guitar-controls {
  display: flex;
  flex-direction: column;
  gap: var(--touch-spacing);
  width: 100%;
  margin-bottom: var(--spacing-xs);
}

.volume-control {
    width: 25%;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: var(--touch-spacing);
}

.volume-icon {
    width: 40px;
    height: 40px;
    fill: var(--color-text-secondary);
    flex-shrink: 0;
    cursor: pointer;
    border-radius: 6px;
    transition: all 0.3s ease;
}

.volume-icon:hover {
    fill: var(--color-primary);
    background-color: var(--color-blue-dark);
}

.volume-slider {
    flex-grow: 1;
    -webkit-appearance: none;
    appearance: none;
    height: 20px;
    cursor: pointer;
    outline: none;
    border-radius: 8px;
    background: linear-gradient(to right, 
        var(--track-fill-color, var(--color-green-medium)) var(--value-percent, 75%), 
        var(--color-blue-dark) var(--value-percent, 75%)
    );
}

/* WebKit browsers (Chrome, Safari, Edge) */
.volume-slider::-webkit-slider-track {
    background: transparent;
    border: none;
}

.volume-slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    height: 24px;
    width: 24px;
    margin-top: -2px;
    border-radius: 50%;
    background: var(--color-text-primary);
    border: 3px solid var(--color-green-medium);
    box-shadow: 0 3px 8px rgba(0, 0, 0, 0.4);
    transition: all 0.3s ease;
}

/* Firefox */
.volume-slider::-moz-range-track {
   background: transparent;
   border: none;
}

.volume-slider::-moz-range-thumb {
    height: 20px;
    width: 20px;
    border-radius: 50%;
    background: var(--color-text-primary);
    border: 3px solid var(--color-green-medium);
    cursor: pointer;
    box-shadow: 0 3px 8px rgba(0, 0, 0, 0.4);
    transition: all 0.3s ease;
    border-color: inherit;
}

/* Hover & Active States */
.volume-slider:hover::-webkit-slider-thumb {
    transform: scale(1.1);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.5);
}
.volume-slider:active::-webkit-slider-thumb {
    transform: scale(1.2);
}
.volume-slider:hover::-moz-range-thumb {
    transform: scale(1.1);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.5);
}
.volume-slider:active::-moz-range-thumb {
    transform: scale(1.2);
}

/* Focus states - Outline removed */
.volume-slider:focus {
    outline: none;
}

.volume-value {
    min-width: 40px;
    text-align: right;
    font-size: 20px;
    font-weight: 600;
    color: var(--color-text-secondary);
    transition: color 0.3s ease;
}

/* Muted state */
.volume-control.muted .volume-slider {
    --track-fill-color: var(--color-danger);
}

/* Muted Thumb - Background changed to make it solid */
.volume-control.muted .volume-slider::-webkit-slider-thumb {
    background: var(--color-danger);
    border-color: var(--color-danger);
}
.volume-control.muted .volume-slider::-moz-range-thumb {
    background: var(--color-danger);
    border-color: var(--color-danger);
}
.volume-control.muted .volume-icon {
    fill: var(--color-danger);
}

/* Touch-friendly improvements */
@media (pointer: coarse) {
    .volume-slider { height: 20px; }
    .volume-slider::-webkit-slider-thumb { height: 24px; width: 24px; margin-top: -2px; }
    .volume-slider::-moz-range-thumb { height: 24px; width: 24px; }
    .volume-icon { width: 32px; height: 32px; padding: 12px; }
}

.volume-icon:focus {
    outline: none;
}

.volume-control.audio-uninitialized * {
    cursor: pointer !important;
    pointer-events: auto !important;
}

.volume-control.audio-uninitialized .volume-slider {
    opacity: 0.7;
    /* Make it look disabled but keep it functional for clicks */
    filter: grayscale(50%);
}

/* When audio is ready, restore normal appearance */
.volume-control.audio-ready .volume-slider {
    opacity: 1;
    filter: none;
}

/* Container for all controls */
.controls-container,
.audio-controls-container {
  display: flex;
  gap: calc(var(--spacing-unit) * 2);
  padding: var(--spacing-unit);
  flex-wrap: wrap;
}

.control-section {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--spacing-unit);
}

.control-section h3 {
  margin: 0;
  font-size: 16px;
  font-weight: 600;
  color: var(--color-text-primary);
  text-align: center;
}

.vertical-controls {
  display: flex;
  gap: calc(var(--spacing-unit) * 1.5);
}

/* Vertical volume control modifications */
.volume-control.vertical {
  width: auto;
  height: 200px;
  max-width: none;
  flex-direction: column;
  justify-content: flex-start;
  margin-bottom: 0;
  gap: calc(var(--spacing-unit) / 2);
}

.control-label {
  font-size: 12px;
  font-weight: 500;
  color: var(--color-text-secondary);
  text-align: center;
  margin: 0;
  white-space: nowrap;
}

/* Vertical slider styling */
.vertical-slider {
  writing-mode: bt-lr; /* IE */
  -webkit-appearance: slider-vertical; /* WebKit */
  width: 20px;
  height: 120px;
  flex-grow: 0;
  background: linear-gradient(
    to top,
    var(--track-fill-color, var(--color-green-medium)) var(--value-percent, 75%),
    var(--color-blue-dark) var(--value-percent, 75%)
  );
  cursor: pointer;
  outline: none;
  border-radius: 8px;
}

/* WebKit browsers (Chrome, Safari, Edge) - Vertical */
.vertical-slider::-webkit-slider-track {
  background: transparent;
  border: none;
  width: 20px;
}

.vertical-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  height: 20px;
  width: 20px;
  border-radius: 50%;
  background: var(--color-text-primary);
  border: 3px solid var(--color-green-medium);
  box-shadow: 0 3px 8px rgba(0, 0, 0, 0.4);
  transition: all 0.3s ease;
  cursor: pointer;
  /* Center the thumb on vertical track */
  margin-left: 0;
  margin-top: 0;
}

/* Firefox - Vertical */
.vertical-slider::-moz-range-track {
  background: transparent;
  border: none;
  width: 20px;
  height: 120px;
}

.vertical-slider::-moz-range-thumb {
  height: 14px;
  width: 14px;
  border-radius: 50%;
  background: var(--color-text-primary);
  border: 3px solid var(--color-green-medium);
  cursor: pointer;
  box-shadow: 0 3px 8px rgba(0, 0, 0, 0.4);
  transition: all 0.3s ease;
  /* Remove default border and center */
  border-color: var(--color-green-medium);
  margin: 0;
}

/* Hover & Active States for Vertical Sliders */
.vertical-slider:hover::-webkit-slider-thumb,
.vertical-slider:hover::-moz-range-thumb {
  transform: scale(1.1);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.5);
}

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

/* Focus states */
.vertical-slider:focus {
  outline: none;
}

/* Value display for vertical sliders */
.volume-control.vertical .volume-value {
  min-width: 60px;
  text-align: center;
  font-size: 12px;
  font-weight: 500;
}

/* Remove volume icon for these controls */
.volume-control.vertical .volume-icon {
  display: none;
}

/* Muted state for vertical sliders */
.volume-control.vertical.muted .vertical-slider {
  --track-fill-color: var(--color-danger);
}

.volume-control.vertical.muted .vertical-slider::-webkit-slider-thumb,
.volume-control.vertical.muted .vertical-slider::-moz-range-thumb {
  background: var(--color-danger);
  border-color: var(--color-danger);
}

/* Touch-friendly improvements for vertical sliders */
@media (pointer: coarse) {
  .vertical-slider {
    width: 24px;
  }
  .vertical-slider::-webkit-slider-thumb {
    height: 24px;
    width: 24px;
  }
  .vertical-slider::-moz-range-thumb {
    height: 18px;
    width: 18px;
  }
}

/* Audio state classes */
.volume-control.vertical.audio-uninitialized * {
  cursor: pointer !important;
  pointer-events: auto !important;
}

.volume-control.vertical.audio-uninitialized .vertical-slider {
  opacity: 0.7;
  filter: grayscale(50%);
}

.volume-control.vertical.audio-ready .vertical-slider {
  opacity: 1;
  filter: none;
}

/* Wrapper and Footer */
.controls-footer,
.outer-wrapper {
  background: #04273c;
  flex-grow: 1;
  display: flex;
  flex-direction: column;
  align-items: center; /* Horizontally centers all direct children */
  padding: calc(var(--spacing-unit) * 2);
  gap: calc(var(--spacing-unit) * 1.5);
  width: 100%;
  max-width: 1400px;
}

/* Preset Controls */
.preset-controls {
  display: flex;
  gap: calc(var(--spacing-unit) * 2);
  flex-wrap: wrap;
  justify-content: center;
  align-items: flex-start;
}

.preset-section {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: calc(var(--spacing-unit) * 0.5);
}

.preset-section h4 {
  margin: 0;
  font-size: 14px;
  font-weight: 600;
  color: var(--color-text-primary);
  text-align: center;
}

.button-row {
  display: flex;
  gap: calc(var(--spacing-unit) * 0.5);
  flex-wrap: wrap;
  justify-content: center;
}

.btn--compact {
  padding: 6px 12px;
  font-size: 12px;
  font-weight: 500;
  border-radius: 6px;
  border: none;
  cursor: pointer;
  transition: all 0.2s ease;
  white-space: nowrap;
}

.btn--primary {
  background-color: var(--color-primary, #007bff);
  color: white;
}

.btn--primary:hover {
  background-color: var(--color-primary-dark, #0056b3);
}

.btn--secondary {
  background-color: var(--color-secondary, #6c757d);
  color: white;
}

.btn--secondary:hover {
  background-color: var(--color-secondary-dark, #545b62);
}

.instrument-selector {
  min-width: 150px;
  margin-bottom: var(--spacing-md);
}

.form-select {
  padding: 8px 12px;
  font-size: 14px;
  background-color: #295570;
  color: var(--color-text-primary);
  cursor: pointer;
  width: 100%;
}

.form-select:focus {
  outline: none;
  box-shadow: 0 0 0 2px rgba(0, 123, 255, 0.25);
}

.form-select:hover {
  border-color: var(--color-primary, #007bff);
}

/* Responsive adjustments */
@media (max-width: 768px) {
  .controls-container,
  .audio-controls-container {
    flex-direction: column;
    align-items: center;
  }
  .vertical-controls {
    flex-wrap: wrap;
    justify-content: center;
  }
  .volume-control.vertical {
    height: 150px;
  }
  .vertical-slider {
    height: 100px;
  }
  .preset-controls {
    flex-direction: column;
    align-items: center;
  }
  .button-row {
    flex-direction: column;
    width: 100%;
  }
  .btn--compact {
    width: 100%;
    max-width: 200px;
  }
}

.score-viewer {
  width: 100%;
  min-height: var(--score-min-height-mobile);
  background-color: #FFFFFF;
  color: var(--color-blue-darkest);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius);
  padding: var(--spacing-sm);
  margin-bottom: var(--spacing-md);
  flex: 1 1 auto;
  overflow-y: auto;
  display: flex;
  justify-content: center;
  align-items: center;
}

.score-viewer__container {
  width: 100%;
  height: 100%;
  overflow-x: auto;
  overflow-y: hidden;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: auto;
  scrollbar-gutter: stable;
  display: flex;
  justify-content: safe center; /* This is the key fix */
  align-items: center;
}

.score-viewer__content {
  display: inline-block;
}

#score {
  user-select: none;
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  touch-action: pan-x;
}

/* ==========================================================================
   7. Instrument Panel (Mobile Optimized)
   ========================================================================== */
.instrument-panel {
  width: 100%;
    max-width: var(--max-width-main);
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
  position: relative;
}


.instrument-panel__spectrum {
  width: 100%;
  min-height: 120px;
  background-color: #000;
  border-radius: var(--border-radius);
}

.instrument-panel__keyboard {
  width: 100%;
  min-height: var(--keyboard-min-height-mobile);
  background-color: var(--color-surface);
  border-radius: var(--border-radius);
  overflow: hidden;
  touch-action: manipulation;
  -webkit-user-select: none;
  -moz-user-select: none;
  user-select: none;
  -webkit-touch-callout: none;
}

/* Piano Key Styles */
.instrument-panel__keyboard .white { 
  fill: #FFFFFF; 
  stroke: #444; 
  stroke-width: 1;
}

.instrument-panel__keyboard .black { 
  fill: #333333; 
  stroke: #000; 
  stroke-width: 1;
}

.instrument-panel__keyboard .white.pressed { 
  fill: #D1D5DB; 
}

.instrument-panel__keyboard .black.pressed { 
  fill: #555555; 
}

/* Hand Position Highlighting */
.instrument-panel__keyboard .left-white  { fill: var(--color-blue-light) !important; }
.instrument-panel__keyboard .left-black  { fill: var(--color-blue-dark) !important; }
.instrument-panel__keyboard .middle      { fill: var(--color-green-light) !important; }
.instrument-panel__keyboard .right-white { fill: var(--color-peach-light) !important; }
.instrument-panel__keyboard .right-black { fill: var(--color-peach-dark) !important; }

/* Chord Highlighting */
.instrument-panel__keyboard .chord-root  { fill: var(--color-blue-light) !important; }
.instrument-panel__keyboard .chord-third { fill: var(--color-green-light) !important; }
.instrument-panel__keyboard .chord-fifth { fill: var(--color-peach-light) !important; }

/* Hand Overlay */
#handOverlay {
  position: absolute;
  height: 20px;
  background: var(--color-primary);
  border-radius: 10px;
  top: -25px;
  cursor: grab;
  touch-action: none;
  backdrop-filter: blur(2px);
  z-index: 5;
  min-width: var(--touch-target-min);
}

#handOverlay.chord-mode {
  background: var(--color-primary);
  border: 2px solid var(--color-info);
}

/* ==========================================================================
   8. Guitar Instrument Styles
   ========================================================================== */

.guitar-wrapper {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  justify-content: center;
  width: 100%;
  margin: 0 auto;
  flex-direction: column;
}

.guitar-fretboard {
  position: relative;
  width: 100%;
  height: var(--guitar-fretboard-height);
  background: linear-gradient(to bottom, #8B4513 0%, #D2691E 50%, #8B4513 100%);
  border-radius: var(--border-radius);
  box-shadow: inset 0 2px 10px rgba(0,0,0,0.3);
  user-select: none;
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  overflow: hidden;
  touch-action: manipulation;
}

.guitar-string-container {
  position: absolute;
  left: 0;
  width: 100%;
  height: var(--guitar-string-height);
  display: flex;
  align-items: center;
  border-bottom: 1px solid rgba(0,0,0,0.2);
}

.guitar-string-container.string-1 { top: calc(var(--guitar-fretboard-height) * 5 / 6); }
.guitar-string-container.string-2 { top: calc(var(--guitar-fretboard-height) * 4 / 6); }
.guitar-string-container.string-3 { top: calc(var(--guitar-fretboard-height) * 3 / 6); }
.guitar-string-container.string-4 { top: calc(var(--guitar-fretboard-height) * 2 / 6); }
.guitar-string-container.string-5 { top: calc(var(--guitar-fretboard-height) * 1 / 6); }
.guitar-string-container.string-6 { 
  top: 0; 
  border-top: 1px solid rgba(0,0,0,0.2); 
}

.guitar-string-line {
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 100%;
  background: linear-gradient(to bottom, #C0C0C0, #808080, #C0C0C0);
  z-index: 1;
}

.string-line-6 { height: 4px; }
.string-line-5 { height: 3.5px; }
.string-line-4 { height: 3px; }
.string-line-3 { height: 2.5px; }
.string-line-2 { height: 2px; }
.string-line-1 { height: 1.5px; }

.fret-position {
  position: absolute;
  top: 0;
  height: 100%;
  z-index: 2;
  cursor: pointer;
  left: var(--fret-left-position);
  width: var(--fret-width);
  transition: background-color 0.1s ease;
  touch-action: manipulation;
}

.fret-position.fret-nut {
  background: linear-gradient(to bottom, #f5f5dc, #e0e0b8);
  border-right: 4px solid #b39b7d;
  box-shadow: 2px 0 5px rgba(0,0,0,0.2);
}

.fret-position.fret {
  border-left: 1px solid rgba(0,0,0,0.3);
}

.fret-position.hover {
  background-color: rgba(255,255,255,0.1);
}

.finger-position {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 20px;
  height: 20px;
  background: radial-gradient(circle, #444, #000);
  border-radius: 50%;
  transform: translate(-50%, -50%);
  z-index: 4;
  box-shadow: 0 2px 4px rgba(0,0,0,0.5);
  cursor: pointer;
  border: 2px solid rgba(255,255,255,0.3);
  touch-action: manipulation;
}

.strum-area {
  position: absolute;
  right: 0;
  top: 0;
  width: 9%;
  height: var(--guitar-fretboard-height);
  background: rgba(255, 255, 255, 0.05);
  border-left: 1px solid rgba(0,0,0,0.1);
  cursor: pointer;
  z-index: 5;
  transition: background-color 0.2s ease;
  border-top-right-radius: var(--border-radius);
  border-bottom-right-radius: var(--border-radius);
  display: flex;
  align-items: center;
  justify-content: center;
  touch-action: manipulation;
}

.strum-area.hover {
  background-color: rgba(255, 255, 255, 0.15);
}

.strum-area span {
  color: rgba(255, 255, 255, 0.4);
  font-size: var(--font-size-xs);
  font-weight: bold;
  text-align: center;
  pointer-events: none;
  writing-mode: vertical-rl;
  text-orientation: mixed;
}

/* String Control Buttons */
.string-labels-container {
  display: flex;
  flex-direction: row;
  gap: var(--spacing-xs);
  flex-wrap: wrap;
  justify-content: center;
  width: 13%;
}

.string-button-container {
  display: flex;
  gap: var(--spacing-xs);
}

.string-button {
  min-width: 60px;
  min-height: var(--touch-target-min);
  padding: var(--spacing-sm);
  background: linear-gradient(to right, #f8f9fa, #e9ecef);
  border: 1px solid #dee2e6;
  border-radius: var(--border-radius);
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: #495057;
  cursor: pointer;
  transition: all 0.2s ease;
  text-align: center;
  box-shadow: 0 1px 3px rgba(0,0,0,0.1);
  touch-action: manipulation;
}

.string-button:hover {
  background: linear-gradient(to right, #e9ecef, #dee2e6);
}

.string-button.muted {
  opacity: 0.5;
  text-decoration: line-through;
  color: #666;
}

.mute-button {
  width: var(--touch-target-min);
  height: var(--touch-target-min);
  border-radius: 50%;
  border: 1px solid #ccc;
  background: #fff;
  font-size: var(--font-size-xs);
  font-weight: bold;
  cursor: pointer;
  transition: all 0.2s;
  touch-action: manipulation;
}

.mute-button:hover {
  background: #f0f0f0;
  border-color: #999;
}

.mute-button.active {
  background: var(--color-danger);
  color: white;
  border-color: var(--color-danger);
}

/* Guitar String Animations */
@keyframes vibrateJuicy {
  0%   { 
    transform: translateY(-50%) scaleY(1); 
    filter: blur(0px) brightness(1);
    box-shadow: 0 0 0px rgba(255, 255, 255, 0);
  }
  3%   { 
    transform: translateY(calc(-50% - 1.8px)) scaleY(0.92); 
    filter: blur(0.6px) brightness(1.4);
    box-shadow: 0 0 15px rgba(255, 255, 255, 0.9);
  }
  8%   { transform: translateY(calc(-50% + 1.5px)) scaleY(1.08); filter: blur(0.4px) brightness(1.25); }
  15%  { transform: translateY(calc(-50% - 1.2px)) scaleY(0.95); filter: blur(0.3px) brightness(1.15); }
  25%  { transform: translateY(calc(-50% + 1px)) scaleY(1.05); filter: blur(0.25px) brightness(1.1); }
  35%  { transform: translateY(calc(-50% - 0.8px)) scaleY(0.97); filter: blur(0.2px) brightness(1.08); }
  45%  { transform: translateY(calc(-50% + 0.6px)) scaleY(1.03); filter: blur(0.15px) brightness(1.06); }
  55%  { transform: translateY(calc(-50% - 0.5px)) scaleY(0.98); filter: blur(0.1px) brightness(1.04); }
  65%  { transform: translateY(calc(-50% + 0.3px)) scaleY(1.02); filter: blur(0.08px) brightness(1.03); }
  75%  { transform: translateY(calc(-50% - 0.2px)) scaleY(0.99); filter: blur(0.05px) brightness(1.02); }
  85%  { transform: translateY(calc(-50% + 0.15px)) scaleY(1.01); filter: blur(0.03px) brightness(1.015); }
  92%  { transform: translateY(calc(-50% - 0.1px)) scaleY(0.995); filter: blur(0.02px) brightness(1.01); }
  96%  { transform: translateY(calc(-50% + 0.05px)) scaleY(1.005); filter: blur(0.01px) brightness(1.005); }
  98%  { transform: translateY(calc(-50% - 0.03px)) scaleY(0.998); filter: blur(0.005px) brightness(1.002); }
  100% { 
    transform: translateY(-50%) scaleY(1);
    filter: blur(0px) brightness(1);
    box-shadow: 0 0 0px rgba(255, 255, 255, 0);
  }
}

@keyframes stringGlow {
  0%   { box-shadow: inset 0 0 0px rgba(255, 255, 255, 0); }
  5%   { box-shadow: inset 0 0 25px rgba(255, 255, 255, 0.2); }
  50%  { box-shadow: inset 0 0 15px rgba(255, 255, 255, 0.1); }
  85%  { box-shadow: inset 0 0 8px rgba(255, 255, 255, 0.05); }
  100% { box-shadow: inset 0 0 0px rgba(255, 255, 255, 0); }
}

.guitar-string-container.active .guitar-string-line {
  animation: vibrateJuicy 1.4s cubic-bezier(0, 0, 0.58, 1);
}

.guitar-string-container.active {
  animation: stringGlow 1.4s cubic-bezier(0.25, 0.1, 0.25, 1);
}

/* Chord Diagrams */
.chord-diagrams-wrapper {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm);
  justify-content: center;
  margin-bottom: var(--spacing-md);
}

.chord-diagram-container {
  border: 1px solid #ddd;
  border-radius: var(--border-radius);
  background: white;
  padding: var(--spacing-sm);
}

/* ==========================================================================
   9. Button System (Touch Optimized)
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: var(--touch-target-min);
  min-width: var(--touch-target-min);
  padding: var(--spacing-sm) var(--spacing-md);
  font-size: var(--font-size-base);
  font-weight: 600;
  line-height: 1.2;
  border: none;
  border-radius: var(--border-radius);
  background-color: var(--color-secondary);
  color: var(--color-text-primary);
  cursor: pointer;
  text-decoration: none;
  transition: all 0.2s ease;
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
  user-select: none;
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  text-align: center;
  white-space: nowrap;
}

.btn:hover,
.btn:focus {
  background-color: var(--color-blue-light);
  outline: none;
}

.btn:active {
  /* No transform needed */
}

/* Button Variants */
.btn--primary {
  background-color: var(--color-green-lightest);
  color: var(--color-green-darkest);
}

.btn--primary:hover,
.btn--primary:focus {
  background-color: var(--color-green-light);
}

.btn--danger {
  background-color: var(--color-peach-light);
  color: var(--color-peach-darkest);
}

.btn--danger:hover,
.btn--danger:focus {
  background-color: var(--color-peach-medium);
}

.btn--info {
  background-color: var(--color-blue-lightest);
  color: var(--color-blue-darkest);
}

.btn--info:hover,
.btn--info:focus {
  background-color: var(--color-blue-light);
}

.btn--secondary {
  background-color: var(--color-secondary);
  color: white;
}

.btn--secondary:hover {
  background-color: var(--color-blue-dark);
}

.btn--compact {
  padding: var(--spacing-xs) var(--spacing-sm);
  font-size: var(--font-size-sm);
  min-height: 40px;
  background-color: var(--color-blue-lightest);
  color: var(--color-blue-darkest);
}

.btn--toggle {
  background-color: var(--color-blue-lightest);
  color: var(--color-blue-darkest);
}

.btn--toggle.is-active {
  background-color: var(--color-green-lightest);
  color: var(--color-green-darkest);
}

/* ==========================================================================
   10. Main Controls (Mobile Layout)
   ========================================================================== */
.main-controls {
  width: 100%;
  background-color: var(--color-surface);
  padding: var(--spacing-sm);
  border-radius: var(--border-radius);
  margin-bottom: var(--spacing-sm);
}

.controls-button-row {
  display: flex;
  flex-direction: column;
  gap: var(--touch-spacing);
  margin-bottom: var(--spacing-sm);
}

.controls-button-row:last-child {
  margin-bottom: 0;
}

.main-controls__chord-interface {
  width: 100%;
  padding-top: var(--spacing-md);
  border-top: 1px solid var(--color-border);
  margin-top: var(--spacing-md);
}

.chord-grid {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm);
  justify-content: center;
}

.chord-section {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-md);
}
/* ==========================================================================
   11. Form Controls (Touch Optimized)
   ========================================================================== */
.control-row {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
}

.control-label {
  font-weight: 600;
  font-size: var(--font-size-sm);
  color: var(--color-text-primary);
}

/* Input Styles */
.time-signature-input,
.tempo-input,
.measure-input,
.chord-input,
.form-select {
  min-height: var(--touch-target-min);
  padding: var(--spacing-sm);
  border-radius: var(--border-radius);
  font-size: var(--font-size-base);
  background: var(--color-blue-darkest);
  color: var(--color-text-primary);
  transition: all 0.2s ease;
  touch-action: manipulation;
  width: 100%;
}

.time-signature-input:focus,
.tempo-input:focus,
.measure-input:focus,
.chord-input:focus,
.form-select:focus {
  outline: none;
  box-shadow: 0 0 0 3px rgba(118, 181, 149, 0.2);
}

/* Control Groups */
.time-signature-controls,
.tempo-controls,
.measure-controls {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.time-signature-separator {
  font-size: var(--font-size-xl);
  font-weight: bold;
  color: var(--color-text-secondary);
  text-align: center;
  padding: var(--spacing-xs);
}

/* ==========================================================================
   12. Note Palette & Editor (Mobile Optimized)
   ========================================================================== */
.note-palette-container {
  background: rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(20px);
  padding: var(--spacing-md);
  margin-bottom: var(--spacing-md);
}

.palette-header {
  color: var(--color-text-primary);
  font-size: var(--font-size-sm);
  font-weight: 600;
  margin-bottom: var(--spacing-sm);
  text-align: center;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.chord-palette-container {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(80px, 1fr));
  gap: var(--touch-spacing);
  justify-items: center;
}

.note-palette {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(80px, 1fr));
  gap: var(--touch-spacing);
  justify-items: center;
}

.palette-note {
  width: 100%;
  min-width: 80px;
  max-width: 120px;
  min-height: var(--touch-target-min);
  background: var(--color-green-lightest);
  color: #000;
  cursor: pointer;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  font-size: var(--font-size-lg);
  font-weight: 600;
  transition: all 0.2s ease;
  user-select: none;
  touch-action: manipulation;
}

.palette-note:hover,
.palette-note:active {
  background: var(--color-peach-light);
}

.note-duration {
  font-size: var(--font-size-xs);
  margin-top: 2px;
  opacity: 0.8;
  font-weight: 500;
}

/* ==========================================================================
   13. Side Panel & Editor (Mobile Adapted)
   ========================================================================== */
.piano-app__side-panel {
  display: none; /* Hidden on mobile by default */
}

.floating-panel {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: calc(100% - 2rem);
  max-width: 400px;
  max-height: 80vh;
  background: rgba(30, 41, 59, 0.95);
  backdrop-filter: blur(20px);
  padding: var(--spacing-md);
  z-index: 1000;
  overflow-y: auto;
  color: white;
}

.floating-panel.visible {
  display: block;
  animation: panelSlideIn 0.3s ease-out forwards;
}

.floating-panel.hidden {
  display: none;
}

@keyframes panelSlideIn {
  from { 
    opacity: 0; 
    transform: translate(-50%, -50%) scale(0.98); 
  }
  to { 
    opacity: 1;
    transform: translate(-50%, -50%) scale(1);
  }
}

.editor-widget {
  margin-bottom: var(--spacing-md);
}

.editor-widget__title {
  font-size: var(--font-size-sm);
  font-weight: 600;
  margin-bottom: var(--spacing-sm);
  color: #94a3b8;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.editor-widget__content--note-list {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm);
  padding: var(--spacing-sm);
  background: rgba(255, 255, 255, 0.05);
  border-radius: var(--border-radius);
}

.note-editor {
  background: rgba(255, 255, 255, 0.08);
  border-radius: var(--border-radius);
  padding: var(--spacing-md);
  margin-top: var(--spacing-md);
  border: 1px solid rgba(255, 255, 255, 0.1);
}

.note-editor__header {
  color: white;
  font-size: var(--font-size-base);
  font-weight: 600;
  margin-bottom: var(--spacing-md);
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

/* ==========================================================================
   14. Chord Search (Mobile Optimized)
   ========================================================================== */
.chord-search-container {
  position: relative;
  margin: var(--spacing-md) 0;
}

.chord-suggestions {
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  background: white;
  border: 2px solid var(--color-primary);
  border-top: none;
  border-radius: 0 0 var(--border-radius) var(--border-radius);
  max-height: 200px;
  overflow-y: auto;
  z-index: 1000;
  display: none;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
}

.chord-suggestion {
  padding: var(--spacing-sm) var(--spacing-md);
  cursor: pointer;
  border-bottom: 1px solid #eee;
  font-size: var(--font-size-base);
  min-height: var(--touch-target-min);
  display: flex;
  align-items: center;
  color: var(--color-blue-darkest);
  touch-action: manipulation;
}

.chord-suggestion:hover,
.chord-suggestion.highlighted {
  background-color: #f0f8ff;
}

.no-results {
  padding: var(--spacing-sm) var(--spacing-md);
  color: #666;
  font-style: italic;
  font-size: var(--font-size-sm);
}

/* ==========================================================================
   15. Utility Classes
   ========================================================================== */
.hidden {
  display: none !important;
}

.hidden-input {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.button-group {
  display: flex;
  flex-direction: column;
  gap: var(--touch-spacing);
}

.audio-uninitialized .volume-slider,
.audio-uninitialized .vertical-slider {
  opacity: 0.7;
  filter: grayscale(50%);
}

/* Muted States */
.volume-control.muted .volume-slider,
.volume-control.vertical.muted .vertical-slider {
  --track-fill-color: var(--color-danger);
}

.volume-control.muted .volume-slider::-webkit-slider-thumb,
.volume-control.muted .volume-slider::-moz-range-thumb,
.volume-control.vertical.muted .vertical-slider::-webkit-slider-thumb,
.volume-control.vertical.muted .vertical-slider::-moz-range-thumb {
  background: var(--color-danger);
  border-color: var(--color-danger);
}

.volume-control.muted .volume-icon {
  fill: var(--color-danger);
}

/* ==========================================================================
   16. TABLET BREAKPOINT (768px and up)
   ========================================================================== */
@media (min-width: 768px) {
  :root {
    --container-padding: var(--spacing-lg);
    --score-min-height-mobile: 250px;
    --keyboard-min-height-mobile: 140px;
    --guitar-fretboard-height: 250px;
  }

  .piano-app__content-area {
    max-width: var(--max-width-tablet);
    padding: var(--container-padding);
    gap: var(--spacing-lg);
  }

  .piano-app__header-title {
    font-size: var(--font-size-4xl);
  }

  .playback-controls,
  .guitar-controls {
    flex-direction: row;
    justify-content: center;
    flex-wrap: wrap;
  }

  .controls-button-row {
    flex-direction: row;
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--spacing-sm);
  }

  .time-signature-controls,
  .tempo-controls,
  .measure-controls {
    flex-direction: row;
    align-items: center;
  }

  .note-palette {
    grid-template-columns: repeat(auto-fit, minmax(100px, 1fr));
    gap: var(--spacing-sm);
  }

  .palette-note {
    min-width: 100px;
    height: 60px;
  }

  .floating-panel {
    width: calc(100% - 4rem);
    max-width: 500px;
  }

  .guitar-wrapper {
    flex-direction: row;
    align-items: center;
  }

  .string-labels-container {
    flex-direction: column;
    align-items: flex-start;
  }

  .string-button {
    min-width: 100px;
  }

  .controls-container,
  .audio-controls-container {
    flex-direction: row;
    justify-content: center;
  }

  .vertical-controls {
    flex-direction: row;
  }
}

/* ==========================================================================
   17. DESKTOP BREAKPOINT (1024px and up)
   ========================================================================== */
@media (min-width: 1024px) {
  :root {
    --container-padding: var(--spacing-xl);
    --score-min-height-mobile: 300px;
    --keyboard-min-height-mobile: 160px;
    --guitar-fretboard-height: 280px;
  }

  .piano-app {
    flex-direction: row;
  }

  .piano-app__content-area {
    max-width: var(--max-width-desktop);
    gap: var(--spacing-xl);
  }

  .piano-app__side-panel {
    display: block;
    width: 320px;
    min-height: 100vh;
    background: rgba(30, 41, 59, 0.95);
    backdrop-filter: blur(10px);
    padding: var(--spacing-xl);
    border-radius: 0 var(--border-radius-lg) var(--border-radius-lg) 0;
    overflow-y: auto;
    flex-shrink: 0;
  }

.piano-app__side-panel.visible {
    display: block;
}

  .note-palette {
    grid-template-columns: repeat(6, 1fr);
  }

  .controls-button-row {
    gap: var(--spacing-md);
  }

  .button-group {
    flex-direction: row;
  }

  .chord-grid {
    gap: var(--spacing-sm);
  }

  .preset-controls {
    flex-direction: row;
    justify-content: space-around;
  }

  .button-row {
    flex-direction: row;
  }
}

/* ==========================================================================
   18. LARGE DESKTOP BREAKPOINT (1280px and up)
   ========================================================================== */
@media (min-width: 1280px) {
  .piano-app__header-title {
    font-size: 3.5rem;
  }

  .note-palette {
    grid-template-columns: repeat(8, 1fr);
  }

  .controls-button-row {
    gap: var(--spacing-lg);
  }
}

/* ==========================================================================
   19. High DPI / Retina Display Optimizations
   ========================================================================== */
@media (-webkit-min-device-pixel-ratio: 2), (min-resolution: 192dpi) {
  .instrument-panel__keyboard .white,
  .instrument-panel__keyboard .black {
    stroke-width: 0.5;
  }
}

/* ==========================================================================
   20. Touch Device Optimizations
   ========================================================================== */
@media (pointer: coarse) {
  :root {
    --touch-target-min: 48px;
    --touch-spacing: 12px;
  }

  .btn {
    min-height: 48px;
    padding: var(--spacing-sm) var(--spacing-lg);
  }

  .volume-slider,
  .vertical-slider {
    height: 48px;
  }

  .volume-slider::-webkit-slider-thumb,
  .volume-slider::-moz-range-thumb {
    height: 28px;
    width: 28px;
  }

  .vertical-slider::-webkit-slider-thumb,
  .vertical-slider::-moz-range-thumb {
    height: 22px;
    width: 22px;
  }

  .palette-note {
    min-height: 48px;
  }

  .chord-suggestion {
    min-height: 48px;
    padding: var(--spacing-md) var(--spacing-lg);
  }
}

/* ==========================================================================
   21. Print Styles
   ========================================================================== */
@media print {
  .playback-controls,
  .main-controls,
  .volume-control,
  .piano-app__side-panel,
  .guitar-wrapper .string-labels-container {
    display: none;
  }

  .score-viewer {
    background: white;
    box-shadow: none;
    border: none;
  }

  body {
    background: white;
    color: black;
  }
}

/* ==========================================================================
   22. Reduced Motion Support
   ========================================================================== */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* ==========================================================================
   23. Focus Management for Accessibility
   ========================================================================== */
.btn:focus-visible,
.volume-slider:focus-visible,
.vertical-slider:focus-visible,
.chord-input:focus-visible,
.form-select:focus-visible,
.palette-note:focus-visible,
.guitar-fretboard *:focus-visible {
  outline: 3px solid var(--color-green-lightest);
  outline-offset: 2px;
}

/* Hide focus outline for mouse users */
.btn:focus:not(:focus-visible),
.volume-slider:focus:not(:focus-visible),
.vertical-slider:focus:not(:focus-visible),
.chord-input:focus:not(:focus-visible),
.form-select:focus:not(:focus-visible),
.palette-note:focus:not(:focus-visible) {
  outline: none;
}