:root {
  /* Primitive Color Tokens */
  --color-white: rgba(255, 255, 255, 1);
  --color-black: rgba(0, 0, 0, 1);
  --color-cream-50: rgba(252, 252, 249, 1);
  --color-cream-100: rgba(255, 255, 253, 1);
  --color-gray-200: rgba(245, 245, 245, 1);
  --color-gray-300: rgba(167, 169, 169, 1);
  --color-gray-400: rgba(119, 124, 124, 1);
  --color-slate-500: rgba(98, 108, 113, 1);
  --color-brown-600: rgba(94, 82, 64, 1);
  --color-charcoal-700: rgba(31, 33, 33, 1);
  --color-charcoal-800: rgba(38, 40, 40, 1);
  --color-slate-900: rgba(19, 52, 59, 1);
  --color-teal-300: rgba(50, 184, 198, 1);
  --color-teal-400: rgba(45, 166, 178, 1);
  --color-teal-500: rgba(33, 128, 141, 1);
  --color-teal-600: rgba(29, 116, 128, 1);
  --color-teal-700: rgba(26, 104, 115, 1);
  --color-teal-800: rgba(41, 150, 161, 1);
  --color-red-400: rgba(255, 84, 89, 1);
  --color-red-500: rgba(192, 21, 47, 1);
  --color-orange-400: rgba(230, 129, 97, 1);
  --color-orange-500: rgba(168, 75, 47, 1);

  /* Semantic Colors */
  --color-background: #f8fafc;
  --color-surface: #ffffff;
  --color-text: var(--color-slate-900);
  --color-text-secondary: var(--color-slate-500);
  --color-primary: #3b82f6;
  --color-primary-hover: #2563eb;
  --color-secondary: var(--color-teal-500);
  --color-secondary-hover: var(--color-teal-600);
  --color-success: #10b981;
  --color-warning: #f59e0b;
  --color-error: #ef4444;
  --color-border: var(--color-gray-200);
  --color-border-focus: var(--color-primary);

  /* Typography */
  --font-family-base: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --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: 1.875rem;
  --font-size-4xl: 2.25rem;

  /* Spacing */
  --spacing-1: 0.25rem;
  --spacing-2: 0.5rem;
  --spacing-3: 0.75rem;
  --spacing-4: 1rem;
  --spacing-5: 1.25rem;
  --spacing-6: 1.5rem;
  --spacing-8: 2rem;
  --spacing-10: 2.5rem;
  --spacing-12: 3rem;
  --spacing-16: 4rem;

  /* Border Radius */
  --border-radius-sm: 0.25rem;
  --border-radius-md: 0.375rem;
  --border-radius-lg: 0.5rem;
  --border-radius-xl: 0.75rem;

  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
}

/* Reset & Base Styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
  line-height: 1.6;
}

body {
  font-family: var(--font-family-base);
  font-size: var(--font-size-base);
  color: var(--color-text);
  background-color: var(--color-background);
  line-height: 1.6;
}

/* Layout Components */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-4);
}

/* Header */
.header {
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  color: white;
  padding: var(--spacing-8) 0;
  text-align: center;
  margin-bottom: var(--spacing-8);
}

.header__title {
  font-size: var(--font-size-4xl);
  font-weight: 700;
  margin-bottom: var(--spacing-2);
}

.header__subtitle {
  font-size: var(--font-size-lg);
  opacity: 0.9;
}

/* App Grid */
.app-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--spacing-6);
}

@media (min-width: 768px) {
  .app-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .app-grid {
    grid-template-columns: 2fr 1fr;
    grid-template-areas:
      "lyrics chords"
      "structure structure"
      "resources resources";
  }

  .lyrics-section {
    grid-area: lyrics;
  }

  .chords-section {
    grid-area: chords;
  }

  .structure-section {
    grid-area: structure;
  }

  .resources-section {
    grid-area: resources;
  }
}

/* Card Component */
.card {
  background: var(--color-surface);
  border-radius: var(--border-radius-lg);
  box-shadow: var(--shadow-md);
  overflow: hidden;
  transition: box-shadow 0.3s ease;
}

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

.card__header {
  background: linear-gradient(135deg, #f1f5f9, #e2e8f0);
  padding: var(--spacing-4) var(--spacing-6);
  border-bottom: 1px solid var(--color-border);
}

.card__header h2 {
  font-size: var(--font-size-xl);
  font-weight: 600;
  color: var(--color-text);
  margin: 0;
}

.card__body {
  padding: var(--spacing-6);
}

/* Form Components */
.form-group {
  margin-bottom: var(--spacing-5);
}

.form-label {
  display: block;
  font-weight: 500;
  margin-bottom: var(--spacing-2);
  color: var(--color-text);
}

.form-control {
  width: 100%;
  padding: var(--spacing-3) var(--spacing-4);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius-md);
  font-size: var(--font-size-base);
  font-family: inherit;
  background: var(--color-surface);
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.form-control:focus {
  outline: none;
  border-color: var(--color-border-focus);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.form-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--spacing-4);
}

@media (min-width: 768px) {
  .form-grid {
    grid-template-columns: 1fr 1fr;
  }
}

.textarea-large {
  min-height: 120px;
  resize: vertical;
  font-family: 'Courier New', monospace;
  line-height: 1.5;
}

/* Button Components */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-2);
  padding: var(--spacing-3) var(--spacing-5);
  border: none;
  border-radius: var(--border-radius-md);
  font-size: var(--font-size-base);
  font-weight: 500;
  text-decoration: none;
  cursor: pointer;
  transition: all 0.2s ease;
  margin-bottom: var(--spacing-4);
}

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

.btn-primary:hover {
  background: var(--color-primary-hover);
  transform: translateY(-1px);
}

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

.btn-secondary:hover {
  background: var(--color-secondary-hover);
  transform: translateY(-1px);
}

.btn-icon {
  font-size: var(--font-size-lg);
}

/* Chord Suggestions */
.chord-suggestions {
  margin-top: var(--spacing-4);
}

.chord-progression {
  background: #f8fafc;
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius-md);
  padding: var(--spacing-4);
  margin-bottom: var(--spacing-3);
}

.chord-progression h4 {
  color: var(--color-primary);
  margin-bottom: var(--spacing-2);
  font-size: var(--font-size-lg);
}

.chord-sequence {
  display: flex;
  gap: var(--spacing-2);
  margin-bottom: var(--spacing-2);
  flex-wrap: wrap;
}

.chord {
  background: var(--color-primary);
  color: white;
  padding: var(--spacing-2) var(--spacing-3);
  border-radius: var(--border-radius-sm);
  font-weight: 500;
  font-size: var(--font-size-sm);
}

.chord-description {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  font-style: italic;
}

/* Structure Builder */
.structure-builder {
  margin: var(--spacing-4) 0;
}

.structure-elements {
  display: flex;
  gap: var(--spacing-2);
  margin-bottom: var(--spacing-4);
  flex-wrap: wrap;
}

.structure-element {
  background: var(--color-secondary);
  color: white;
  padding: var(--spacing-2) var(--spacing-4);
  border-radius: var(--border-radius-md);
  cursor: grab;
  user-select: none;
  font-size: var(--font-size-sm);
  font-weight: 500;
  transition: all 0.2s ease;
}

.structure-element:hover {
  transform: scale(1.05);
}

.structure-element:active {
  cursor: grabbing;
}

.structure-timeline {
  min-height: 100px;
  border: 2px dashed var(--color-border);
  border-radius: var(--border-radius-md);
  padding: var(--spacing-4);
  background: #fafbfc;
  display: flex;
  gap: var(--spacing-2);
  align-items: center;
  flex-wrap: wrap;
}

.structure-timeline.drag-over {
  border-color: var(--color-primary);
  background: rgba(59, 130, 246, 0.05);
}

.timeline-placeholder {
  color: var(--color-text-secondary);
  font-style: italic;
  text-align: center;
  width: 100%;
}

.timeline-element {
  background: var(--color-primary);
  color: white;
  padding: var(--spacing-2) var(--spacing-3);
  border-radius: var(--border-radius-sm);
  font-size: var(--font-size-sm);
  font-weight: 500;
  position: relative;
}

.timeline-element .remove-btn {
  position: absolute;
  top: -8px;
  right: -8px;
  background: var(--color-error);
  color: white;
  border: none;
  border-radius: 50%;
  width: 20px;
  height: 20px;
  font-size: 12px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* Resources Grid */
.resources-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--spacing-6);
}

@media (min-width: 768px) {
  .resources-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

.resource-category h3 {
  color: var(--color-primary);
  margin-bottom: var(--spacing-3);
  font-size: var(--font-size-lg);
}

.resource-list {
  list-style: none;
}

.resource-list li {
  padding: var(--spacing-2) 0;
  border-bottom: 1px solid #f1f5f9;
  font-size: var(--font-size-sm);
}

.resource-list li:last-child {
  border-bottom: none;
}

.theme-tags {
  display: flex;
  gap: var(--spacing-2);
  flex-wrap: wrap;
}

.theme-tag {
  background: rgba(59, 130, 246, 0.1);
  color: var(--color-primary);
  padding: var(--spacing-1) var(--spacing-3);
  border-radius: var(--border-radius-xl);
  font-size: var(--font-size-sm);
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s ease;
}

.theme-tag:hover {
  background: rgba(59, 130, 246, 0.2);
  transform: scale(1.05);
}

.ai-tools {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-3);
}

.ai-tool {
  background: #f8fafc;
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius-md);
  padding: var(--spacing-3);
  transition: all 0.2s ease;
}

.ai-tool:hover {
  background: #f1f5f9;
  transform: translateY(-1px);
}

.ai-tool-name {
  font-weight: 600;
  color: var(--color-primary);
  margin-bottom: var(--spacing-1);
}

.ai-tool-description {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
}

/* Section Description */
.section-description {
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-4);
  font-size: var(--font-size-sm);
}

/* Footer */
.footer {
  background: var(--color-slate-900);
  color: white;
  text-align: center;
  padding: var(--spacing-6) 0;
  margin-top: var(--spacing-12);
}

.footer p {
  font-size: var(--font-size-sm);
  opacity: 0.8;
}

/* Responsive Design */
@media (max-width: 767px) {
  .container {
    padding: 0 var(--spacing-3);
  }

  .header {
    padding: var(--spacing-6) 0;
  }

  .header__title {
    font-size: var(--font-size-3xl);
  }

  .card__body {
    padding: var(--spacing-4);
  }

  .app-grid {
    gap: var(--spacing-4);
  }

  .structure-elements {
    justify-content: center;
  }

  .chord-sequence {
    justify-content: center;
  }
}

/* Animation Classes */
.fade-in {
  animation: fadeIn 0.5s ease-in;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Loading States */
.loading {
  opacity: 0.6;
  pointer-events: none;
  position: relative;
}

.loading::after {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 20px;
  height: 20px;
  margin: -10px 0 0 -10px;
  border: 2px solid var(--color-primary);
  border-top: 2px solid transparent;
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

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