:root {
  --bg-light: #f8f8f8;
  --primary-light: #fff;
  --secondary-light: #f0f0f0;
  --hover-light: #e0e0e0;
  --border-light: #000000;
  --text-light: #333;
  --shadow-light: rgba(0, 0, 0, 0.1);

  --bg-dark: #222;
  --primary-dark: #333;
  --secondary-dark: #444;
  --hover-dark: #555;
  --border-dark: #ffffff;
  --text-dark: #f0f0f0;

  --accent-primary: #4CAF50;
  --accent-hover: #45a049;
  --accent-focus: #4CAF50;
  --focus-shadow: rgba(76, 175, 80, 0.3);

  --spacing-xs: 2px;
  --spacing-sm: 5px;
  --spacing-md: 10px;
  --spacing-lg: 20px;

  --min-touch-target: 44px;
  --icon-size: 24px;

  --transition-fast: 0.2s ease;
  --transition-normal: 0.3s ease;

  --radius-sm: 3px;
  --radius-md: 4px;
  --radius-lg: 5px;
  --radius-round: 50%;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Arial, sans-serif;
  background-color: var(--bg-light);
  color: var(--text-light);
  line-height: 1.5;
  transition: background-color var(--transition-normal), color var(--transition-normal);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--spacing-lg);
}

.header {
  text-align: left;
  margin-bottom: var(--spacing-lg);
}

.dark-mode-toggle-container {
  position: absolute;
  top: 20px;
  right: 20px;
  display: flex;
  align-items: right;
  gap: var(--spacing-sm);
}

.main-content {
  display: flex;
  flex-wrap: wrap;
  margin-top: var(--spacing-lg);
}

.canvas-area {
  flex: 0 0 800px;
  width: 80%;
}

.working-area {
  flex: 1;
  display: flex;
  flex-direction: row;
  gap: var(--spacing-lg);
}

.controls-area {
  flex: 1;
  width: 225px;
}

canvas {
  display: block;
  margin: 0 auto;
  background-color: var(--primary-light);
}

#canvas-container {
  margin: var(--spacing-lg) 0 var(--spacing-md);
  width: 800px;
  height: 600px;
  position: relative;
  overflow: auto;
}

.controls-area,
.canvas-area {
  background-color: var(--primary-light);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-light);
  padding: var(--spacing-md);
  box-shadow: 0 1px 3px var(--shadow-light);
  margin-bottom: var(--spacing-lg);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-sm) var(--spacing-md);
  background-color: var(--secondary-light);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  cursor: pointer;
  font-size: 12px;
  transition: all var(--transition-fast);
  -webkit-tap-highlight-color: transparent;
  -webkit-user-select: none;
  user-select: none;
}

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

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

button:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible {
  box-shadow: 0 0 0 3px var(--focus-shadow);
}

.toggle-container {
  display: flex;
  align-items: center;
  margin-left: var(--spacing-sm);
}

.toggle-label {
  margin-right: 8px;
  font-size: 14px;
}

.toggle {
  width: 40px;
  height: 20px;
  background-color: var(--secondary-light);
  border-radius: 10px;
  position: relative;
  cursor: pointer;
  transition: all var(--transition-normal);
}

.toggle::after {
  content: '';
  width: 18px;
  height: 18px;
  background-color: var(--primary-light);
  border-radius: var(--radius-round);
  position: absolute;
  top: 1px;
  left: 1px;
  transition: all var(--transition-normal);
}

.toggle.active {
  background-color: var(--accent-primary);
}

.toggle.active::after {
  left: 21px;
}

body.dark-mode .toggle {
  background-color: var(--secondary-dark);
}

body.dark-mode .toggle::after {
  background-color: var(--text-dark);
}

body.dark-mode .toggle.active {
  background-color: var(--accent-primary);
}

.color-row {
  display: flex;
  align-items: center;
  gap: 8px;
}

.btn-icon {
  padding: 4px 6px;
  line-height: 1;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.working-color-control {
  display: flex;
  align-items: center;
  gap: 4px;
}

.working-color-control input[type="color"] {
  margin-right: 10px;
}

.working-color-control span {
  font-family: monospace;
}

h3 {
  margin: 0 0 8px;
  font-size: 14px;
}

.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;
}

.skip-link {
  position: absolute;
  top: -40px;
  left: 6px;
  background: #000;
  color: #fff;
  padding: 8px;
  text-decoration: none;
  z-index: 100;
}

.skip-link:focus {
  top: 6px;
}

[hidden] {
  display: none !important;
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-md);
}

.control-group label {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
  font-size: 14px;
}

.control-group input[type="number"],
.control-group select {
  padding: 6px var(--spacing-md);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  background-color: var(--bg-light);
  font-size: 14px;
}

.control-group input[type="range"] {
  width: 100%;
}

.algo-summary {
  font-size: 12px;
  font-style: italic;
  color: #666;
  margin: var(--spacing-xs) 0 var(--spacing-md);
  min-height: 1.2em;
}

.canvas-actions {
  display: flex;
  gap: var(--spacing-sm);
  margin-top: var(--spacing-md);
}

.panel {
  margin-bottom: var(--spacing-md);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: var(--spacing-sm);
}

.panel summary {
  cursor: pointer;
  font-weight: 600;
  font-size: 14px;
  padding: var(--spacing-sm);
}

.panel[open] summary {
  margin-bottom: var(--spacing-sm);
  border-bottom: 1px solid var(--border-light);
}

.legend-content {
  padding: var(--spacing-sm);
  font-size: 13px;
  line-height: 1.6;
}

.swatch {
  display: inline-block;
  width: 16px;
  height: 16px;
  border: 1px solid var(--border-light);
  border-radius: 2px;
  vertical-align: middle;
  margin-right: 4px;
}

.help-text {
  font-size: 12px;
  color: #666;
  margin-top: 2px;
}

body.dark-mode {
  background-color: var(--bg-dark);
  color: var(--text-dark);
}

body.dark-mode canvas,
body.dark-mode .controls-area,
body.dark-mode .canvas-area {
  background-color: var(--primary-dark);
  border-color: var(--border-dark);
}

body.dark-mode .btn {
  background-color: var(--secondary-dark);
  border-color: var(--border-dark);
  color: var(--text-dark);
}

body.dark-mode .btn:hover {
  background-color: var(--hover-dark);
}

body.dark-mode .control-group input[type="number"],
body.dark-mode .control-group select {
  background-color: var(--secondary-dark);
  border-color: var(--border-dark);
  color: var(--text-dark);
}

body.dark-mode .panel {
  border-color: var(--border-dark);
}

body.dark-mode .panel summary {
  color: var(--text-dark);
}

body.dark-mode .panel[open] summary {
  border-bottom-color: var(--border-dark);
}

body.dark-mode .algo-summary,
body.dark-mode .help-text {
  color: #999;
}

body.dark-mode .swatch {
  border-color: var(--border-dark);
}

@media screen and (max-width: 1024px) {
  .canvas-area {
    flex: 2;
  }

  .controls-area {
    flex: 1;
    width: 250px;
  }
}

@media screen and (max-width: 768px) {
  .container {
    padding: var(--spacing-md);
    max-width: 100%;
  }

  .header h1 {
    font-size: 1.5rem;
    margin: 0.5rem 0;
  }

  .main-content {
    flex-direction: column;
  }

  .canvas-area {
    order: 2;
    flex: 1 1 auto;
    margin-bottom: var(--spacing-lg);
  }

  .controls-area {
    order: 1;
    width: 100%;
  }

  #canvas-container {
    width: 100%;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }

  input[type="number"] {
    min-height: var(--min-touch-target);
    font-size: 16px;
    padding: 12px;
  }
}

@media screen and (max-width: 480px) {
  .container {
    padding: 8px;
  }

  .header h1 {
    font-size: 1.25rem;
  }
}

@media screen and (max-width: 768px) and (orientation: landscape) {
  .container {
    padding: 8px;
  }

  .main-content {
    flex-direction: row;
  }

  .controls-area {
    max-height: calc(100vh - 120px);
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
  }

  .header h1 {
    font-size: 1.25rem;
    margin: 0.25rem 0;
  }
}

@media (hover: none) and (pointer: coarse) {

  button,
  input,
  select {
    min-height: 48px;
    min-width: 48px;
  }
}

@media (prefers-contrast: high) {
  button {
    border: 2px solid;
  }
}

@media (prefers-reduced-motion: reduce) {

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

@supports (-webkit-touch-callout: none) {
  .container {
    min-height: -webkit-fill-available;
  }
}

@media (display-mode: standalone) {
  .container {
    padding-top: env(safe-area-inset-top, 20px);
    padding-bottom: env(safe-area-inset-bottom, 20px);
    padding-left: env(safe-area-inset-left, 20px);
    padding-right: env(safe-area-inset-right, 20px);
  }
}

@media print {
  .container {
    max-width: none;
    padding: 0;
  }

  .controls-area {
    display: none;
  }

  .canvas-area {
    width: 100%;
  }

  #canvas-container {
    break-inside: avoid;
  }
}