/* CSS Variables for Theme Management */
:root {
  --color-primary: #00ADB5;
  --color-secondary: #FFD369;
  --color-dark-1: #222831;
  --color-dark-2: #393E46;
  --color-light: #EEEEEE;
  --color-white: #FFFFFF;
  --color-error: #FF6B6B;
  --color-success: #4ECDC4;
  --color-warning: #FFE66D;
  
  --font-family: 'Segoe UI', Tahoma, Geneva, Verdana, 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;
  
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  
  --border-radius: 8px;
  --border-radius-lg: 12px;
  --box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  --box-shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.15);
  
  --transition: all 0.3s ease;
}

/* Dark Theme Variables */
[data-theme="dark"] {
  --bg-primary: var(--color-dark-1);
  --bg-secondary: var(--color-dark-2);
  --bg-tertiary: #2C3E50;
  --text-primary: var(--color-light);
  --text-secondary: #BDC3C7;
  --text-muted: #95A5A6;
  --border-color: #34495E;
}

/* Light Theme Variables */
[data-theme="light"] {
  --bg-primary: var(--color-white);
  --bg-secondary: var(--color-light);
  --bg-tertiary: #F8F9FA;
  --text-primary: var(--color-dark-1);
  --text-secondary: var(--color-dark-2);
  --text-muted: #6C757D;
  --border-color: #DEE2E6;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--bg-primary);
  transition: var(--transition);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* App Container */
.app {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* Container */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-md);
  width: 100%;
}

/* Header */
.header {
  background-color: var(--bg-secondary);
  border-bottom: 1px solid var(--border-color);
  padding: var(--spacing-lg) 0;
  position: relative;
}

.header__container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-md);
  text-align: center;
  position: relative;
}

.header__title {
  font-size: var(--font-size-3xl);
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: var(--spacing-sm);
}

.header__subtitle {
  font-size: var(--font-size-lg);
  color: var(--text-secondary);
  font-weight: 300;
}

/* Theme Toggle */
.theme-toggle {
  position: absolute;
  top: 50%;
  right: var(--spacing-md);
  transform: translateY(-50%);
  background: var(--color-primary);
  border: none;
  border-radius: 50%;
  width: 50px;
  height: 50px;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
}

.theme-toggle:hover {
  background: var(--color-dark-2);
  transform: translateY(-50%) scale(1.1);
}

.theme-toggle__icon {
  font-size: var(--font-size-xl);
}

/* Main Content */
.main {
  flex: 1;
  padding: var(--spacing-2xl) 0;
}

/* Button Styles */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-md) var(--spacing-lg);
  border: none;
  border-radius: var(--border-radius);
  font-size: var(--font-size-base);
  font-weight: 500;
  text-decoration: none;
  cursor: pointer;
  transition: var(--transition);
  gap: var(--spacing-sm);
  min-height: 44px;
}

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

.btn--primary:hover {
  background-color: var(--color-dark-2);
  transform: translateY(-2px);
}

.btn--secondary {
  background-color: var(--color-secondary);
  color: var(--color-dark-1);
}

.btn--secondary:hover {
  background-color: var(--color-warning);
  transform: translateY(-2px);
}

.btn--small {
  padding: var(--spacing-sm) var(--spacing-md);
  font-size: var(--font-size-sm);
  min-height: 36px;
}

.btn--large {
  padding: var(--spacing-lg) var(--spacing-xl);
  font-size: var(--font-size-lg);
  min-height: 52px;
}

.btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none;
}

/* Upload Section */
.upload-section {
  margin-bottom: var(--spacing-2xl);
}

.upload-area {
  border: 2px dashed var(--border-color);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-2xl);
  text-align: center;
  background-color: var(--bg-secondary);
  transition: var(--transition);
  cursor: pointer;
  position: relative;
}

.upload-area:hover,
.upload-area--dragover {
  border-color: var(--color-primary);
  background-color: var(--bg-tertiary);
  transform: translateY(-2px);
}

.upload-area__content {
  pointer-events: none;
}

.upload-area__icon {
  font-size: 4rem;
  margin-bottom: var(--spacing-lg);
  opacity: 0.7;
}

.upload-area__title {
  font-size: var(--font-size-2xl);
  font-weight: 600;
  margin-bottom: var(--spacing-md);
  color: var(--text-primary);
}

.upload-area__description {
  font-size: var(--font-size-lg);
  color: var(--text-secondary);
  margin-bottom: var(--spacing-sm);
}

.upload-area__formats {
  font-size: var(--font-size-sm);
  color: var(--text-muted);
  margin-bottom: var(--spacing-lg);
}

.upload-area__input {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  opacity: 0;
  cursor: pointer;
}

.upload-area__button {
  pointer-events: auto;
}

/* File Info Section */
.file-info {
  margin-bottom: var(--spacing-2xl);
}

.file-info__card {
  background-color: var(--bg-secondary);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-xl);
  box-shadow: var(--box-shadow);
}

.file-info__header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--spacing-lg);
  flex-wrap: wrap;
  gap: var(--spacing-md);
}

.file-info__title {
  font-size: var(--font-size-xl);
  font-weight: 600;
  color: var(--text-primary);
}

.file-info__details {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-lg);
}

.file-info__item {
  display: flex;
  justify-content: space-between;
  padding: var(--spacing-sm) 0;
  border-bottom: 1px solid var(--border-color);
}

.file-info__label {
  font-weight: 500;
  color: var(--text-secondary);
}

.file-info__value {
  color: var(--text-primary);
  font-weight: 400;
}

/* Audio Preview */
.audio-preview {
  margin-bottom: var(--spacing-lg);
}

.audio-preview__title {
  font-size: var(--font-size-lg);
  font-weight: 600;
  margin-bottom: var(--spacing-md);
  color: var(--text-primary);
}

.audio-player {
  width: 100%;
}

.audio-player__element {
  width: 100%;
  height: 40px;
  border-radius: var(--border-radius);
}

/* Separation Controls */
.separation-controls__title {
  font-size: var(--font-size-lg);
  font-weight: 600;
  margin-bottom: var(--spacing-md);
  color: var(--text-primary);
}

.separation-options {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-lg);
}

.checkbox-option {
  display: flex;
  align-items: center;
  cursor: pointer;
  padding: var(--spacing-md);
  border-radius: var(--border-radius);
  background-color: var(--bg-tertiary);
  transition: var(--transition);
}

.checkbox-option:hover {
  background-color: var(--bg-primary);
}

.checkbox-option input[type="checkbox"] {
  display: none;
}

.checkbox-option__checkmark {
  width: 20px;
  height: 20px;
  border: 2px solid var(--color-primary);
  border-radius: 4px;
  margin-right: var(--spacing-md);
  position: relative;
  transition: var(--transition);
}

.checkbox-option input[type="checkbox"]:checked + .checkbox-option__checkmark {
  background-color: var(--color-primary);
}

.checkbox-option input[type="checkbox"]:checked + .checkbox-option__checkmark::after {
  content: '✓';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: var(--color-white);
  font-size: var(--font-size-sm);
  font-weight: bold;
}

.checkbox-option__label {
  font-size: var(--font-size-base);
  color: var(--text-primary);
  font-weight: 500;
}

/* Processing Section */
.processing-section {
  margin-bottom: var(--spacing-2xl);
}

.processing-card {
  background-color: var(--bg-secondary);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-xl);
  box-shadow: var(--box-shadow);
  text-align: center;
}

.processing-card__header {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-lg);
}

.processing-card__title {
  font-size: var(--font-size-xl);
  font-weight: 600;
  color: var(--text-primary);
}

.processing-card__spinner {
  width: 24px;
  height: 24px;
  border: 3px solid var(--border-color);
  border-top: 3px solid var(--color-primary);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

.progress-bar {
  width: 100%;
  height: 8px;
  background-color: var(--border-color);
  border-radius: 4px;
  margin-bottom: var(--spacing-lg);
  overflow: hidden;
}

.progress-bar__fill {
  height: 100%;
  background-color: var(--color-primary);
  border-radius: 4px;
  transition: width 0.3s ease;
  width: 0%;
}

.processing-card__status {
  font-size: var(--font-size-lg);
  color: var(--text-primary);
  margin-bottom: var(--spacing-sm);
}

.processing-card__time {
  font-size: var(--font-size-base);
  color: var(--text-secondary);
}

/* Results Section */
.results-section {
  margin-bottom: var(--spacing-2xl);
}

.results-card {
  background-color: var(--bg-secondary);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-xl);
  box-shadow: var(--box-shadow);
}

.results-card__title {
  font-size: var(--font-size-xl);
  font-weight: 600;
  color: var(--color-success);
  text-align: center;
  margin-bottom: var(--spacing-xl);
}

.track-result {
  background-color: var(--bg-tertiary);
  border-radius: var(--border-radius);
  padding: var(--spacing-lg);
  margin-bottom: var(--spacing-lg);
}

.track-result__header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--spacing-md);
  flex-wrap: wrap;
  gap: var(--spacing-md);
}

.track-result__title {
  font-size: var(--font-size-lg);
  font-weight: 600;
  color: var(--text-primary);
}

.results-actions {
  display: flex;
  gap: var(--spacing-md);
  justify-content: center;
  flex-wrap: wrap;
  margin-top: var(--spacing-lg);
}

/* Error Section */
.error-section {
  margin-bottom: var(--spacing-2xl);
}

.error-card {
  background-color: var(--bg-secondary);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-xl);
  box-shadow: var(--box-shadow);
  text-align: center;
  border: 2px solid var(--color-error);
}

.error-card__icon {
  font-size: 4rem;
  margin-bottom: var(--spacing-lg);
}

.error-card__title {
  font-size: var(--font-size-xl);
  font-weight: 600;
  color: var(--color-error);
  margin-bottom: var(--spacing-md);
}

.error-card__message {
  font-size: var(--font-size-base);
  color: var(--text-secondary);
  margin-bottom: var(--spacing-lg);
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

/* Footer */
.footer {
  background-color: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: var(--spacing-lg) 0;
  margin-top: auto;
}

.footer__text {
  text-align: center;
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
}

.footer__link {
  color: var(--color-primary);
  text-decoration: none;
  transition: var(--transition);
}

.footer__link:hover {
  color: var(--color-dark-2);
  text-decoration: underline;
}

/* Loading Overlay */
.loading-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.7);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 9999;
}

.loading-spinner {
  width: 60px;
  height: 60px;
  border: 6px solid rgba(255, 255, 255, 0.3);
  border-top: 6px solid var(--color-primary);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

/* Toast Notifications */
.toast-container {
  position: fixed;
  top: var(--spacing-lg);
  right: var(--spacing-lg);
  z-index: 10000;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.toast {
  background-color: var(--bg-secondary);
  border-radius: var(--border-radius);
  padding: var(--spacing-md) var(--spacing-lg);
  box-shadow: var(--box-shadow-lg);
  border-left: 4px solid var(--color-primary);
  max-width: 400px;
  transform: translateX(100%);
  animation: slideIn 0.3s ease forwards;
}

.toast--success {
  border-left-color: var(--color-success);
}

.toast--error {
  border-left-color: var(--color-error);
}

.toast--warning {
  border-left-color: var(--color-warning);
}

@keyframes slideIn {
  to {
    transform: translateX(0);
  }
}

.toast__message {
  color: var(--text-primary);
  font-size: var(--font-size-sm);
  margin: 0;
}

/* Responsive Design */
@media (max-width: 768px) {
  .container {
    padding: 0 var(--spacing-sm);
  }
  
  .header__container {
    padding: 0 var(--spacing-sm);
  }
  
  .theme-toggle {
    right: var(--spacing-sm);
    width: 40px;
    height: 40px;
  }
  
  .upload-area {
    padding: var(--spacing-lg);
  }
  
  .upload-area__title {
    font-size: var(--font-size-xl);
  }
  
  .file-info__header {
    flex-direction: column;
    align-items: flex-start;
  }
  
  .file-info__details {
    grid-template-columns: 1fr;
  }
  
  .separation-options {
    gap: var(--spacing-sm);
  }
  
  .track-result__header {
    flex-direction: column;
    align-items: flex-start;
  }
  
  .results-actions {
    flex-direction: column;
  }
  
  .toast-container {
    top: var(--spacing-sm);
    right: var(--spacing-sm);
    left: var(--spacing-sm);
  }
  
  .toast {
    max-width: none;
  }
}

@media (max-width: 480px) {
  .header__title {
    font-size: var(--font-size-2xl);
  }
  
  .header__subtitle {
    font-size: var(--font-size-base);
  }
  
  .btn {
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: var(--font-size-sm);
  }
  
  .btn--large {
    padding: var(--spacing-md) var(--spacing-lg);
    font-size: var(--font-size-base);
  }
  
  .upload-area__icon {
    font-size: 3rem;
  }
  
  .file-info__card,
  .processing-card,
  .results-card,
  .error-card {
    padding: var(--spacing-lg);
  }
}

/* Accessibility Improvements */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* Focus Styles for Accessibility */
.btn:focus,
.upload-area:focus-within,
.checkbox-option:focus-within,
.theme-toggle:focus {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* High Contrast Mode Support */
@media (prefers-contrast: high) {
  :root {
    --box-shadow: 0 0 0 1px var(--border-color);
    --box-shadow-lg: 0 0 0 2px var(--border-color);
  }
}

/* Print Styles */
@media print {
  .theme-toggle,
  .upload-area,
  .processing-section,
  .audio-player,
  .btn {
    display: none !important;
  }
  
  .file-info__card,
  .results-card {
    box-shadow: none;
    border: 1px solid #000;
  }
}