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

:root {
  --color-primary: #2563eb;
  --color-primary-hover: #1d4ed8;
  --color-bg: #f8fafc;
  --color-surface: #ffffff;
  --color-border: #e2e8f0;
  --color-text: #1e293b;
  --color-text-muted: #64748b;
  --color-success: #22c55e;
  --color-error: #ef4444;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --transition: 0.2s ease;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  min-height: 100vh;
}

/* Container */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 24px 16px;
}

/* Header */
.header {
  text-align: center;
  margin-bottom: 32px;
}

.header h1 {
  font-size: 2rem;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 8px;
}

.subtitle {
  color: var(--color-text-muted);
  font-size: 1rem;
}


/* Main Content */
.main-content {
  display: flex;
  flex-direction: column;
  gap: 32px;
}

/* Upload Section */
.upload-section {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}

.upload-area {
  position: relative;
  background: var(--color-surface);
  border: 2px dashed var(--color-border);
  border-radius: var(--radius-lg);
  padding: 32px;
  cursor: pointer;
  transition: border-color var(--transition), background-color var(--transition);
  min-height: 200px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.upload-area:hover {
  border-color: var(--color-primary);
  background-color: #f1f5f9;
}

.upload-area.drag-over {
  border-color: var(--color-primary);
  background-color: #dbeafe;
  border-style: solid;
}

.upload-area.has-image {
  border-style: solid;
  border-color: var(--color-success);
  padding: 8px;
}

.upload-area.has-image .upload-placeholder {
  display: none;
}

.upload-area.has-image .preview-image {
  display: block;
}

.upload-placeholder {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  text-align: center;
}

.upload-icon {
  width: 48px;
  height: 48px;
  color: var(--color-text-muted);
}

.upload-text {
  font-size: 1rem;
  font-weight: 500;
  color: var(--color-text);
}

.upload-hint {
  font-size: 0.875rem;
  color: var(--color-text-muted);
}

.preview-image {
  display: none;
  max-width: 100%;
  max-height: 300px;
  object-fit: contain;
  border-radius: var(--radius-sm);
}

.file-input {
  position: absolute;
  inset: 0;
  opacity: 0;
  cursor: pointer;
}


/* Settings Panel */
.settings-panel {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  padding: 24px;
  box-shadow: var(--shadow-sm);
}

.settings-title {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 20px;
  color: var(--color-text);
}

.setting-group {
  margin-bottom: 20px;
}

.setting-group:last-child {
  margin-bottom: 0;
}

.setting-label {
  display: block;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text);
  margin-bottom: 8px;
}

.setting-slider {
  width: 100%;
  height: 8px;
  border-radius: 4px;
  background: var(--color-border);
  outline: none;
  -webkit-appearance: none;
  appearance: none;
}

.setting-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--color-primary);
  cursor: pointer;
  transition: transform var(--transition);
}

.setting-slider::-webkit-slider-thumb:hover {
  transform: scale(1.1);
}

.setting-slider::-moz-range-thumb {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--color-primary);
  cursor: pointer;
  border: none;
}

.color-toggle {
  display: flex;
  gap: 8px;
}

.color-btn {
  flex: 1;
  padding: 10px 16px;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text);
  cursor: pointer;
  transition: all var(--transition);
}

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

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

/* Sync Checkbox */
.sync-checkbox {
  display: flex;
  align-items: center;
  gap: 8px;
  cursor: pointer;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text);
}

.sync-checkbox-input {
  width: 18px;
  height: 18px;
  border: 2px solid var(--color-border);
  border-radius: 4px;
  background: var(--color-surface);
  cursor: pointer;
  transition: all var(--transition);
  appearance: none;
  -webkit-appearance: none;
  position: relative;
}

.sync-checkbox-input:hover {
  border-color: var(--color-primary);
}

.sync-checkbox-input:checked {
  background: var(--color-primary);
  border-color: var(--color-primary);
}

.sync-checkbox-input:checked::after {
  content: '✓';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: white;
  font-size: 12px;
  font-weight: bold;
}

.sync-checkbox-text {
  user-select: none;
}


/* Preview Section */
.preview-section {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  padding: 24px;
  box-shadow: var(--shadow-sm);
}

.preview-title {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 20px;
  color: var(--color-text);
}

.preview-container {
  position: relative;
  background: #f1f5f9;
  border-radius: var(--radius-md);
  min-height: 200px;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

#preview-canvas {
  display: none;
  max-width: 100%;
  max-height: 500px;
}

.preview-container.has-preview #preview-canvas {
  display: block;
}

.preview-container.has-preview .preview-placeholder {
  display: none;
}

.preview-placeholder {
  color: var(--color-text-muted);
  font-size: 0.875rem;
}

/* Download Section */
.download-section {
  display: flex;
  justify-content: center;
}

.download-controls {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
}

.format-selector {
  display: flex;
  align-items: center;
  gap: 8px;
}

.format-label {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text);
}

.format-select {
  padding: 8px 12px;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
  color: var(--color-text);
  font-size: 0.875rem;
  cursor: pointer;
  transition: border-color var(--transition);
}

.format-select:hover {
  border-color: var(--color-primary);
}

.format-select:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.download-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 32px;
  background: var(--color-primary);
  color: white;
  border: none;
  border-radius: var(--radius-md);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
  box-shadow: var(--shadow-md);
}

.download-btn:hover:not(:disabled) {
  background: var(--color-primary-hover);
  transform: translateY(-1px);
}

.download-btn:disabled {
  background: var(--color-border);
  color: var(--color-text-muted);
  cursor: not-allowed;
  box-shadow: none;
}

.download-icon {
  width: 20px;
  height: 20px;
}

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


/* Responsive Design */
@media (max-width: 768px) {
  .container {
    padding: 16px 12px;
  }

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

  .upload-section {
    grid-template-columns: 1fr;
    gap: 16px;
  }

  .upload-area {
    min-height: 160px;
    padding: 24px;
  }

  .upload-icon {
    width: 36px;
    height: 36px;
  }

  .upload-text {
    font-size: 0.875rem;
  }

  .settings-panel,
  .preview-section {
    padding: 16px;
  }

  .settings-title,
  .preview-title {
    font-size: 1.125rem;
  }

  .preview-container {
    min-height: 150px;
  }

  #preview-canvas {
    max-height: 300px;
  }

  .download-controls {
    width: 100%;
  }

  .format-selector {
    justify-content: center;
  }

  .download-btn {
    width: 100%;
    justify-content: center;
    padding: 12px 24px;
  }

  .main-content {
    gap: 24px;
  }
}

@media (max-width: 480px) {
  .color-toggle {
    flex-direction: column;
  }

  .color-btn {
    padding: 12px;
  }
}

/* Error Message */
.error-message {
  background: #fef2f2;
  border: 1px solid #fecaca;
  color: var(--color-error);
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  margin-top: 16px;
}