/**
 * Klangtreppe — Main Stylesheet
 * Dark theme, CSS Grid layout, responsive design.
 */

/* ============================================================
   1. CSS Custom Properties (Design Tokens)
   ============================================================ */

:root {
  /* Colors */
  --color-bg: #1a1a2e;
  --color-bg-viz: #16213e;
  --color-accent: #f0a500;
  --color-accent-hover: #ffb820;
  --color-text: #e0e0e0;
  --color-text-muted: #8888aa;
  --color-control-bg: #1f1f3a;
  --color-control-border: #2a2a4a;
  --color-control-hover: #2a2a50;
  --color-surface: #0f3460;
  --color-error: #ff4444;

  /* Layer colors (Okabe-Ito) */
  --color-layer-0: #E69F00;
  --color-layer-1: #56B4E9;
  --color-layer-2: #009E73;
  --color-layer-3: #F0E442;
  --color-layer-4: #0072B2;
  --color-layer-5: #D55E00;
  --color-layer-6: #CC79A7;
  --color-layer-7: #999999;

  /* Typography */
  --font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  --font-mono: 'SF Mono', 'Fira Code', 'Consolas', monospace;
  --font-size-base: 14px;
  --font-size-sm: 12px;
  --font-size-lg: 16px;
  --font-size-xl: 20px;
  --font-size-h1: 24px;

  /* Spacing */
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 12px;
  --space-lg: 16px;
  --space-xl: 24px;

  /* Layout */
  --header-height: 56px;
  --footer-height: 52px;
  --viz-width: 67%;
  --controls-width: 33%;

  /* Borders */
  --radius-sm: 4px;
  --radius-md: 6px;
  --radius-lg: 8px;

  /* Transitions */
  --transition-fast: 100ms ease;
  --transition-normal: 200ms ease;
}

/* ============================================================
   2. Reset & Base Styles
   ============================================================ */

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

body {
  margin: 0;
  padding: 0;
  height: 100vh;
  overflow: hidden;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: 1.4;

  display: grid;
  grid-template-rows: var(--header-height) 1fr var(--footer-height);
  grid-template-columns: 1fr;
}

/* ============================================================
   3. Header
   ============================================================ */

.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 var(--space-xl);
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-control-border);
  z-index: 5;
}

.header__title {
  display: flex;
  align-items: baseline;
  gap: var(--space-md);
}

.header__title h1 {
  margin: 0;
  font-size: var(--font-size-h1);
  font-weight: 700;
  color: var(--color-accent);
  letter-spacing: -0.5px;
}

.header__subtitle {
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
}

.header__actions {
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

/* ============================================================
   4. Main Layout
   ============================================================ */

.main {
  display: grid;
  grid-template-columns: var(--viz-width) var(--controls-width);
  overflow: hidden;
  min-height: 0;
}

/* ============================================================
   5. Visualization Area
   ============================================================ */

.viz-area {
  display: flex;
  flex-direction: column;
  position: relative;
  min-height: 0;
  background: var(--color-bg-viz);
}

.viz-tabs {
  display: flex;
  flex-shrink: 0;
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-control-border);
  padding: 0 var(--space-sm);
}

.viz-tabs [role="tab"] {
  background: none;
  border: none;
  color: var(--color-text-muted);
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  padding: var(--space-sm) var(--space-lg);
  cursor: pointer;
  border-bottom: 2px solid transparent;
  transition: color var(--transition-normal), border-color var(--transition-normal);
}

.viz-tabs [role="tab"]:hover {
  color: var(--color-text);
}

.viz-tabs [role="tab"][aria-selected="true"] {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

.viz-canvas-container {
  flex: 1;
  min-height: 0;
  position: relative;
}

.viz-canvas-container canvas {
  display: block;
  width: 100%;
  height: 100%;
}

/* ============================================================
   6. Controls Panel (Sidebar)
   ============================================================ */

.controls-panel {
  overflow-y: auto;
  padding: var(--space-lg);
  border-left: 1px solid var(--color-control-border);
  background: var(--color-bg);
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

/* Scrollbar styling for controls panel */
.controls-panel::-webkit-scrollbar {
  width: 6px;
}

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

.controls-panel::-webkit-scrollbar-thumb {
  background: var(--color-control-border);
  border-radius: 3px;
}

.controls-panel::-webkit-scrollbar-thumb:hover {
  background: var(--color-text-muted);
}

/* ============================================================
   7. Control Groups (Fieldsets)
   ============================================================ */

.control-group {
  border: 1px solid var(--color-control-border);
  border-radius: var(--radius-md);
  padding: var(--space-md);
  margin: 0;
  background: var(--color-control-bg);
}

.control-group legend {
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  padding: 0 var(--space-xs);
}

.control-group label {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  margin-top: var(--space-sm);
}

.control-group label input[type="range"] {
  flex: 1;
}

.control-group output {
  font-family: var(--font-mono);
  font-size: var(--font-size-sm);
  color: var(--color-text);
  min-width: 70px;
  text-align: right;
}

/* ============================================================
   8. Buttons
   ============================================================ */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-xs);
  padding: var(--space-sm) var(--space-lg);
  border: 1px solid var(--color-control-border);
  border-radius: var(--radius-md);
  background: var(--color-control-bg);
  color: var(--color-text);
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  cursor: pointer;
  transition: background var(--transition-fast), border-color var(--transition-fast), color var(--transition-fast);
  white-space: nowrap;
}

.btn:hover {
  background: var(--color-control-hover);
  border-color: var(--color-text-muted);
}

/* Primary button (accent color) */
.btn--primary {
  background: var(--color-accent);
  color: #1a1a2e;
  border-color: var(--color-accent);
  font-weight: 600;
}

.btn--primary:hover {
  background: var(--color-accent-hover);
  border-color: var(--color-accent-hover);
}

/* Secondary button */
.btn--secondary {
  background: transparent;
  border-color: var(--color-control-border);
  color: var(--color-text);
}

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

/* Ghost button (minimal) */
.btn--ghost {
  background: transparent;
  border-color: transparent;
  color: var(--color-text-muted);
}

.btn--ghost:hover {
  color: var(--color-text);
  background: rgba(255, 255, 255, 0.05);
}

/* Toggle button */
.btn--toggle {
  margin-top: var(--space-sm);
  width: 100%;
}

.btn--toggle[aria-pressed="true"],
.btn--toggle.btn--active {
  background: rgba(240, 165, 0, 0.15);
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* Icon button (small, square) */
.btn--icon {
  padding: var(--space-xs);
  min-width: 28px;
  min-height: 28px;
  font-size: var(--font-size-sm);
  font-weight: 700;
}

/* Play button */
.btn--play {
  min-width: 130px;
  font-size: var(--font-size-lg);
}

/* Preset button */
.btn--preset {
  padding: var(--space-xs) var(--space-md);
  font-size: var(--font-size-sm);
  border-radius: var(--radius-sm);
}

/* Active state for buttons */
.btn--active,
[role="radio"][aria-checked="true"],
[role="tab"][aria-selected="true"].btn {
  background: rgba(240, 165, 0, 0.15);
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* ============================================================
   9. Button Groups (Radio pattern)
   ============================================================ */

.btn-group {
  display: flex;
  gap: 1px;
  background: var(--color-control-border);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.btn-group [role="radio"] {
  flex: 1;
  background: var(--color-control-bg);
  border: none;
  color: var(--color-text-muted);
  font-family: var(--font-family);
  font-size: var(--font-size-sm);
  padding: var(--space-sm) var(--space-md);
  cursor: pointer;
  transition: background var(--transition-fast), color var(--transition-fast);
  text-align: center;
}

.btn-group [role="radio"]:hover {
  background: var(--color-control-hover);
  color: var(--color-text);
}

.btn-group [role="radio"][aria-checked="true"] {
  background: rgba(240, 165, 0, 0.15);
  color: var(--color-accent);
  font-weight: 600;
}

/* ============================================================
   10. Sliders (Range Inputs)
   ============================================================ */

input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 6px;
  background: var(--color-control-border);
  border-radius: 3px;
  outline: none;
  cursor: pointer;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--color-accent);
  border: 2px solid var(--color-bg);
  cursor: pointer;
  transition: transform var(--transition-fast);
}

input[type="range"]::-webkit-slider-thumb:hover {
  transform: scale(1.2);
}

input[type="range"]::-moz-range-thumb {
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--color-accent);
  border: 2px solid var(--color-bg);
  cursor: pointer;
}

input[type="range"]::-moz-range-track {
  height: 6px;
  background: var(--color-control-border);
  border-radius: 3px;
}

/* ============================================================
   11. Toggle / Checkbox
   ============================================================ */

.toggle-label {
  display: flex !important;
  align-items: center;
  gap: var(--space-sm);
  cursor: pointer;
}

.toggle-label input[type="checkbox"] {
  -webkit-appearance: none;
  appearance: none;
  width: 36px;
  height: 20px;
  background: var(--color-control-border);
  border-radius: 10px;
  position: relative;
  cursor: pointer;
  transition: background var(--transition-normal);
  flex-shrink: 0;
}

.toggle-label input[type="checkbox"]::after {
  content: '';
  position: absolute;
  top: 2px;
  left: 2px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--color-text-muted);
  transition: transform var(--transition-normal), background var(--transition-normal);
}

.toggle-label input[type="checkbox"]:checked {
  background: var(--color-accent);
}

.toggle-label input[type="checkbox"]:checked::after {
  transform: translateX(16px);
  background: #fff;
}

/* ============================================================
   12. Select
   ============================================================ */

select {
  background: var(--color-control-bg);
  color: var(--color-text);
  border: 1px solid var(--color-control-border);
  border-radius: var(--radius-sm);
  padding: var(--space-xs) var(--space-sm);
  font-family: var(--font-family);
  font-size: var(--font-size-sm);
  cursor: pointer;
  flex: 1;
}

select:hover {
  border-color: var(--color-text-muted);
}

/* ============================================================
   13. Layer List
   ============================================================ */

.layer-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
  margin-top: var(--space-sm);
}

.layer-item {
  display: grid;
  grid-template-columns: 12px 1fr auto auto auto auto;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--radius-sm);
  background: rgba(255, 255, 255, 0.02);
  transition: background var(--transition-fast);
}

.layer-item:hover {
  background: rgba(255, 255, 255, 0.05);
}

.layer-item__color {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  flex-shrink: 0;
}

.layer-item__name {
  font-size: var(--font-size-sm);
  color: var(--color-text);
  white-space: nowrap;
}

.layer-item__freq {
  font-family: var(--font-mono);
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  min-width: 60px;
  text-align: right;
}

.layer-item__amp-bar {
  width: 40px;
  height: 6px;
  background: var(--color-control-border);
  border-radius: 3px;
  overflow: hidden;
}

.layer-item__amp-fill {
  height: 100%;
  border-radius: 3px;
  transition: width 50ms linear;
}

.layer-item .btn--solo {
  font-size: 11px;
  padding: 2px 6px;
  min-width: 24px;
  min-height: 24px;
}

.layer-item .btn--mute {
  font-size: 11px;
  padding: 2px 6px;
  min-width: 24px;
  min-height: 24px;
}

.layer-item .btn--solo[aria-pressed="true"] {
  background: rgba(240, 165, 0, 0.2);
  color: var(--color-accent);
  border-color: var(--color-accent);
}

.layer-item .btn--mute[aria-pressed="true"] {
  background: rgba(255, 68, 68, 0.15);
  color: var(--color-error);
  border-color: var(--color-error);
}

/* ============================================================
   14. Discrete Options
   ============================================================ */

.discrete-options {
  margin-top: var(--space-sm);
  padding-top: var(--space-sm);
  border-top: 1px solid var(--color-control-border);
}

.discrete-options[hidden] {
  display: none;
}

/* ============================================================
   15. Footer
   ============================================================ */

.footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 var(--space-xl);
  background: var(--color-bg);
  border-top: 1px solid var(--color-control-border);
  gap: var(--space-lg);
  z-index: 5;
}

.footer__presets {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  flex: 1;
  min-width: 0;
  overflow-x: auto;
}

.footer__label {
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  white-space: nowrap;
  flex-shrink: 0;
}

.preset-buttons {
  display: flex;
  gap: var(--space-xs);
  flex-wrap: wrap;
}

.footer__controls {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  flex-shrink: 0;
}

.volume-control {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: var(--font-size-lg);
}

.volume-control input[type="range"] {
  width: 80px;
}

/* ============================================================
   16. Tutorial Overlay
   ============================================================ */

.tutorial-overlay {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  background: rgba(26, 26, 46, 0.92);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-top: 2px solid var(--color-accent);
  padding: var(--space-lg) var(--space-xl);
  z-index: 10;
}

.tutorial-overlay[hidden] {
  display: none;
}

.tutorial-overlay__content {
  max-width: 600px;
}

.tutorial-overlay__step {
  color: var(--color-accent);
  font-size: var(--font-size-sm);
  font-weight: 600;
  margin: 0 0 var(--space-xs);
}

.tutorial-overlay__title {
  font-size: var(--font-size-xl);
  font-weight: 700;
  margin: 0 0 var(--space-sm);
  color: var(--color-text);
}

.tutorial-overlay__text {
  font-size: var(--font-size-lg);
  line-height: 1.5;
  margin: 0 0 var(--space-lg);
  color: var(--color-text);
}

.tutorial-overlay__nav {
  display: flex;
  gap: var(--space-md);
  align-items: center;
}

.tutorial-overlay__nav .btn--ghost {
  margin-left: auto;
}

/* ============================================================
   17. Tooltip
   ============================================================ */

.tooltip {
  position: fixed;
  z-index: 100;
  background: var(--color-control-bg);
  color: var(--color-text);
  border: 1px solid var(--color-control-border);
  border-radius: var(--radius-md);
  padding: var(--space-sm) var(--space-md);
  font-size: var(--font-size-sm);
  line-height: 1.4;
  max-width: 280px;
  pointer-events: none;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
  transition: opacity var(--transition-fast);
}

.tooltip[hidden] {
  display: none;
}

.tooltip::after {
  content: '';
  position: absolute;
  bottom: -6px;
  left: 50%;
  transform: translateX(-50%);
  width: 0;
  height: 0;
  border-left: 6px solid transparent;
  border-right: 6px solid transparent;
  border-top: 6px solid var(--color-control-border);
}

/* Tooltip positioned below target: arrow points up */
.tooltip--below::after {
  bottom: auto;
  top: -6px;
  border-top: none;
  border-bottom: 6px solid var(--color-control-border);
}

/* Share button copied confirmation */
.btn--copied {
  background: rgba(0, 158, 115, 0.2) !important;
  border-color: #009E73 !important;
  color: #009E73 !important;
}

/* ============================================================
   18. Screen Reader Only
   ============================================================ */

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ============================================================
   19. Focus Styles
   ============================================================ */

:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

:focus:not(:focus-visible) {
  outline: none;
}

/* ============================================================
   20. Transitions & Animations
   ============================================================ */

.btn,
.viz-tabs [role="tab"],
.btn-group [role="radio"],
input[type="range"]::-webkit-slider-thumb,
.toggle-label input[type="checkbox"],
select {
  transition: all var(--transition-fast);
}

/* ============================================================
   21. Responsive: Tablet (≤ 1024px)
   ============================================================ */

@media (max-width: 1024px) {
  :root {
    --viz-width: 60%;
    --controls-width: 40%;
    --header-height: 48px;
    --footer-height: 48px;
  }

  .header {
    padding: 0 var(--space-lg);
  }

  .header__title h1 {
    font-size: var(--font-size-xl);
  }

  .header__subtitle {
    display: none;
  }

  .footer {
    padding: 0 var(--space-lg);
  }

  .footer__presets {
    flex-wrap: wrap;
  }

  .btn--preset {
    font-size: var(--font-size-sm);
    padding: var(--space-xs) var(--space-sm);
  }

  .controls-panel {
    padding: var(--space-md);
  }
}

/* ============================================================
   22. Responsive: Narrow Tablet (≤ 768px)
   ============================================================ */

@media (max-width: 768px) {
  .main {
    grid-template-columns: 1fr;
    grid-template-rows: 1fr auto;
  }

  .controls-panel {
    border-left: none;
    border-top: 1px solid var(--color-control-border);
    max-height: 40vh;
    overflow-y: auto;
  }

  .header__title h1 {
    font-size: var(--font-size-lg);
  }

  .btn--play {
    min-width: 100px;
    font-size: var(--font-size-base);
  }

  .footer__label {
    display: none;
  }

  .preset-buttons {
    flex-wrap: wrap;
  }
}