:root {
  /* Light theme colors */
  --bg-primary: #ffffff;
  --bg-secondary: #f8fafc;
  --bg-tertiary: #f1f5f9;
  --surface: #ffffff;
  --surface-elevated: #f8fafc;
  
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #64748b;
  
  --border-light: #e2e8f0;
  --border-medium: #cbd5e1;
  --border-dark: #94a3b8;
  
  --primary: #3b82f6;
  --primary-hover: #2563eb;
  --secondary: #10b981;
  --secondary-hover: #059669;
  --accent: #f59e0b;
  --danger: #ef4444;
  --warning: #f59e0b;
  --success: #22c55e;
  
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1);
  
  --radius-sm: 6px;
  --radius-md: 8px;
  --radius-lg: 12px;
  
  color-scheme: light dark;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-tertiary: #334155;
    --surface: #1e293b;
    --surface-elevated: #334155;
    
    --text-primary: #f1f5f9;
    --text-secondary: #cbd5e1;
    --text-muted: #94a3b8;
    
    --border-light: #334155;
    --border-medium: #475569;
    --border-dark: #64748b;
  }
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: 'Inter', system-ui, -apple-system, 'Segoe UI', Roboto, Arial, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  font-size: 14px;
}

.container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 24px;
}

/* Header Styles */
.header {
  text-align: center;
  margin-bottom: 32px;
  padding: 24px;
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  border-radius: var(--radius-lg);
  color: white;
  box-shadow: var(--shadow-lg);
}

.header h1 {
  margin: 0 0 8px 0;
  font-size: 2.5rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
}

.header .icon {
  font-size: 2.5rem;
}

.header .subtitle {
  margin: 0;
  font-size: 1.1rem;
  opacity: 0.9;
  font-weight: 400;
}

/* Panel Styles */
.panel {
  background: var(--surface);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 24px;
  margin: 24px 0;
  box-shadow: var(--shadow-sm);
  transition: box-shadow 0.2s ease;
}

.panel:hover {
  box-shadow: var(--shadow-md);
}

.panel h2 {
  margin: 0 0 20px 0;
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 8px;
}

/* Layout Styles */
.row {
  display: flex;
  gap: 16px;
  align-items: center;
  flex-wrap: wrap;
  margin-bottom: 16px;
}

.grid {
  display: grid;
  gap: 16px;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
}

.grid.two {
  grid-template-columns: 1fr 1fr;
}

.grid.three {
  grid-template-columns: repeat(3, 1fr);
}

.grid.four {
  grid-template-columns: repeat(4, 1fr);
}

/* Form Styles */
.form-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
  min-width: 200px;
}

.form-row {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}

label {
  display: flex;
  flex-direction: column;
  gap: 6px;
  font-weight: 500;
  color: var(--text-secondary);
}

label span {
  font-size: 0.875rem;
  font-weight: 500;
}

input, select, textarea {
  background: var(--bg-primary);
  border: 1px solid var(--border-medium);
  color: var(--text-primary);
  border-radius: var(--radius-md);
  padding: 10px 12px;
  font-size: 14px;
  transition: all 0.2s ease;
  font-family: inherit;
}

input:focus, select:focus, textarea:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgb(59 130 246 / 0.1);
}

input[readonly] {
  background: var(--bg-secondary);
  color: var(--text-muted);
  cursor: not-allowed;
}

/* Button Styles */
.btn {
  border: 1px solid var(--border-medium);
  background: var(--surface);
  color: var(--text-primary);
  padding: 10px 16px;
  border-radius: var(--radius-md);
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  font-family: inherit;
  transition: all 0.2s ease;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  text-decoration: none;
}

.btn:hover {
  background: var(--bg-secondary);
  border-color: var(--border-dark);
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn:active {
  transform: translateY(0);
}

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

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

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

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

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

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

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

.btn-small {
  padding: 6px 10px;
  font-size: 12px;
}

.btn-large {
  padding: 14px 20px;
  font-size: 16px;
}

/* Distribution Selection */
.distribution-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 16px;
  margin: 20px 0;
}

.distribution-card {
  background: var(--surface-elevated);
  border: 2px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 20px;
  cursor: pointer;
  transition: all 0.2s ease;
  position: relative;
}

.distribution-card:hover {
  border-color: var(--primary);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.distribution-card.selected {
  border-color: var(--primary);
  background: rgb(59 130 246 / 0.05);
}

.distribution-card .icon {
  font-size: 2rem;
  margin-bottom: 8px;
  display: block;
}

.distribution-card .name {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 4px;
  color: var(--text-primary);
}

.distribution-card .category {
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 8px;
}

.distribution-card .description {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.4;
}

/* Parameter Controls */
.parameter-section {
  background: var(--bg-secondary);
  border-radius: var(--radius-lg);
  padding: 20px;
  margin: 20px 0;
}

.parameter-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
}

.parameter-control {
  background: var(--surface);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 16px;
}

.parameter-control .label {
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
  display: block;
}

.parameter-control input[type="range"] {
  width: 100%;
  margin: 8px 0;
}

.parameter-value {
  font-family: 'SF Mono', 'Monaco', 'Inconsolata', 'Roboto Mono', monospace;
  background: var(--bg-tertiary);
  padding: 4px 8px;
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  color: var(--text-primary);
}

/* Results Section */
.results-grid {
  display: grid;
  grid-template-columns: 1fr 2fr;
  gap: 24px;
  margin-top: 20px;
}

.results-panel {
  background: var(--surface-elevated);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 20px;
}

.results-panel h3 {
  margin: 0 0 16px 0;
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-primary);
}

.stat-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 8px 0;
  border-bottom: 1px solid var(--border-light);
}

.stat-item:last-child {
  border-bottom: none;
}

.stat-label {
  font-weight: 500;
  color: var(--text-secondary);
}

.stat-value {
  font-family: 'SF Mono', 'Monaco', 'Inconsolata', 'Roboto Mono', monospace;
  font-weight: 600;
  color: var(--text-primary);
}

/* Canvas and Visualization */
.visualization-container {
  position: relative;
  background: var(--surface);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.canvas-wrapper {
  position: relative;
  width: 100%;
  height: 400px;
}

canvas {
  width: 100%;
  height: 100%;
  cursor: crosshair;
  background: var(--surface);
}

.chart-controls {
  position: absolute;
  top: 10px;
  right: 10px;
  display: flex;
  gap: 8px;
  z-index: 10;
}

.chart-controls .btn {
  padding: 6px 10px;
  font-size: 12px;
  opacity: 0.8;
}

.chart-controls .btn:hover {
  opacity: 1;
}

/* Tabs */
.tabs {
  display: flex;
  border-bottom: 1px solid var(--border-light);
  margin-bottom: 20px;
}

.tab {
  padding: 12px 20px;
  border: none;
  background: none;
  color: var(--text-secondary);
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  border-bottom: 2px solid transparent;
  transition: all 0.2s ease;
}

.tab:hover {
  color: var(--text-primary);
  background: var(--bg-secondary);
}

.tab.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
}

.tab-content {
  display: none;
}

.tab-content.active {
  display: block;
}

/* Cards */
.card {
  background: var(--surface);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 20px;
  box-shadow: var(--shadow-sm);
  transition: box-shadow 0.2s ease;
}

.card:hover {
  box-shadow: var(--shadow-md);
}

.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-light);
}

.card-title {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-primary);
  margin: 0;
}

/* Progress and Loading */
.progress-bar {
  width: 100%;
  height: 8px;
  background: var(--bg-secondary);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: var(--primary);
  border-radius: var(--radius-sm);
  transition: width 0.3s ease;
}

.loading {
  display: inline-block;
  width: 20px;
  height: 20px;
  border: 2px solid var(--border-light);
  border-radius: 50%;
  border-top-color: var(--primary);
  animation: spin 1s ease-in-out infinite;
}

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

/* Utilities */
.muted {
  color: var(--text-muted);
}

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

.text-secondary {
  color: var(--secondary);
}

.text-danger {
  color: var(--danger);
}

.text-success {
  color: var(--success);
}

.text-center {
  text-align: center;
}

.text-right {
  text-align: right;
}

.mb-0 { margin-bottom: 0; }
.mb-1 { margin-bottom: 8px; }
.mb-2 { margin-bottom: 16px; }
.mb-3 { margin-bottom: 24px; }

.mt-0 { margin-top: 0; }
.mt-1 { margin-top: 8px; }
.mt-2 { margin-top: 16px; }
.mt-3 { margin-top: 24px; }

.p-1 { padding: 8px; }
.p-2 { padding: 16px; }
.p-3 { padding: 24px; }

.hidden {
  display: none;
}

.visible {
  display: block;
}

/* Footer */
.footer {
  text-align: center;
  margin-top: 48px;
  padding: 24px;
  color: var(--text-muted);
  font-size: 0.875rem;
}

/* Responsive Design */
@media (max-width: 1024px) {
  .grid.four {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .results-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 768px) {
  .container {
    padding: 16px;
  }
  
  .header h1 {
    font-size: 2rem;
    flex-direction: column;
    gap: 8px;
  }
  
  .grid.two,
  .grid.three,
  .grid.four {
    grid-template-columns: 1fr;
  }
  
  .distribution-grid {
    grid-template-columns: 1fr;
  }
  
  .parameter-grid {
    grid-template-columns: 1fr;
  }
  
  .row {
    flex-direction: column;
    align-items: stretch;
  }
  
  .tabs {
    overflow-x: auto;
    white-space: nowrap;
  }
}

@media (max-width: 480px) {
  .panel {
    padding: 16px;
  }
  
  .btn {
    width: 100%;
    justify-content: center;
  }
  
  .canvas-wrapper {
    height: 300px;
  }
}