* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --primary-color: #2563eb;
  --primary-hover: #1d4ed8;
  --secondary-color: #64748b;
  --success-color: #10b981;
  --error-color: #ef4444;
  --bg-light: #f8fafc;
  --bg-card: #ffffff;
  --border-color: #e2e8f0;
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  min-height: 100vh;
  padding: 2rem 1rem;
  color: var(--text-primary);
}

.container {
  max-width: 800px;
  margin: 0 auto;
  background: var(--bg-card);
  border-radius: 16px;
  box-shadow: var(--shadow-lg);
  overflow: hidden;
}

/* Header */
header {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  padding: 2rem;
  text-align: center;
}

header h1 {
  font-size: 2rem;
  margin-bottom: 0.5rem;
  font-weight: 700;
}

.subtitle {
  font-size: 1rem;
  opacity: 0.95;
}

/* Main content */
main {
  padding: 2rem;
}

/* Upload zone */
.upload-zone {
  border: 3px dashed var(--border-color);
  border-radius: 12px;
  padding: 3rem 2rem;
  text-align: center;
  cursor: pointer;
  transition: all 0.3s ease;
  background: var(--bg-light);
}

.upload-zone:hover {
  border-color: var(--primary-color);
  background: #eff6ff;
  transform: translateY(-2px);
}

.upload-zone.drag-over {
  border-color: var(--primary-color);
  background: #eff6ff;
  border-style: solid;
}

.upload-icon {
  font-size: 4rem;
  margin-bottom: 1rem;
  opacity: 0.6;
}

.upload-text {
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
  line-height: 1.6;
}

.upload-text strong {
  color: var(--text-primary);
  display: block;
  margin-bottom: 0.25rem;
}

/* Buttons */
.btn {
  padding: 0.75rem 2rem;
  border: none;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

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

.btn-primary:hover {
  background: var(--primary-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
}

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

.btn-secondary:hover {
  background: #475569;
  transform: translateY(-1px);
}

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

/* File info */
.file-info {
  animation: fadeIn 0.3s ease;
}

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

.info-card,
.options-card {
  background: var(--bg-light);
  border-radius: 12px;
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}

.info-card h3,
.options-card h3 {
  font-size: 1.25rem;
  margin-bottom: 1rem;
  color: var(--text-primary);
}

.info-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
  margin-bottom: 1rem;
}

.info-item {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

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

.info-item .value {
  font-size: 1.125rem;
  color: var(--text-primary);
  font-weight: 600;
}

/* Sample preview */
#samplePreview {
  margin-top: 1rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border-color);
}

#samplePreview h4 {
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
  font-weight: 600;
}

#sampleData {
  background: var(--bg-card);
  padding: 1rem;
  border-radius: 8px;
  font-family: 'Courier New', monospace;
  font-size: 0.875rem;
  overflow-x: auto;
  border: 1px solid var(--border-color);
  color: var(--text-primary);
}

/* Options */
.option {
  margin-bottom: 1.5rem;
}

.option:last-child {
  margin-bottom: 0;
}

.checkbox-label {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  cursor: pointer;
  font-weight: 500;
  color: var(--text-primary);
}

.checkbox-label input[type="checkbox"] {
  width: 20px;
  height: 20px;
  cursor: pointer;
  accent-color: var(--primary-color);
}

.option-description {
  margin-top: 0.5rem;
  margin-left: 2rem;
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* Actions */
.actions {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
}

/* Progress */
.progress {
  text-align: center;
  padding: 2rem;
  animation: fadeIn 0.3s ease;
}

.spinner {
  width: 50px;
  height: 50px;
  border: 4px solid var(--border-color);
  border-top-color: var(--primary-color);
  border-radius: 50%;
  animation: spin 1s linear infinite;
  margin: 0 auto 1rem;
}

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

#progressText {
  color: var(--text-secondary);
  font-weight: 500;
}

/* Messages */
.error-message,
.success-message {
  padding: 1rem 1.5rem;
  border-radius: 8px;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-top: 1rem;
  animation: slideIn 0.3s ease;
}

@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateX(-10px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

.error-message {
  background: #fef2f2;
  color: #991b1b;
  border: 1px solid #fecaca;
}

.success-message {
  background: #f0fdf4;
  color: #166534;
  border: 1px solid #bbf7d0;
}

.error-icon,
.success-icon {
  font-size: 1.5rem;
}

/* Footer */
footer {
  background: var(--bg-light);
  padding: 2rem;
  border-top: 1px solid var(--border-color);
}

.info-box h4 {
  font-size: 1rem;
  margin-bottom: 1rem;
  color: var(--text-primary);
}

.info-box ul {
  list-style: none;
}

.info-box li {
  padding: 0.5rem 0;
  color: var(--text-secondary);
  line-height: 1.6;
  font-size: 0.875rem;
}

.info-box li strong {
  color: var(--text-primary);
  font-weight: 600;
}

/* Responsive */
@media (max-width: 640px) {
  body {
    padding: 1rem 0.5rem;
  }

  header h1 {
    font-size: 1.5rem;
  }

  .subtitle {
    font-size: 0.875rem;
  }

  main {
    padding: 1.5rem;
  }

  .upload-zone {
    padding: 2rem 1rem;
  }

  .upload-icon {
    font-size: 3rem;
  }

  .actions {
    flex-direction: column;
  }

  .btn {
    width: 100%;
    justify-content: center;
  }

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

/* Dark mode support (optioneel) */
@media (prefers-color-scheme: dark) {
  /* Kan later toegevoegd worden indien gewenst */
}