:root {
  --primary-color: #4f46e5;
  --primary-hover: #4338ca;
  --success-color: #10b981;
  --error-color: #ef4444;
  --bg-color: #f9fafb;
  --card-bg: #ffffff;
  --text-primary: #111827;
  --text-secondary: #6b7280;
  --border-color: #e5e7eb;
  --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
}

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

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

.container {
  max-width: 600px;
  margin: 0 auto;
  padding: 0 1.5rem;
  width: 100%;
}

header {
  background-color: var(--card-bg);
  border-bottom: 1px solid var(--border-color);
  padding: 2rem 0;
  text-align: center;
}

header h1 {
  font-size: 2rem;
  font-weight: 700;
  color: var(--primary-color);
  margin-bottom: 0.5rem;
}

.tagline {
  color: var(--text-secondary);
  font-size: 1rem;
}

main {
  flex: 1;
  padding: 3rem 0;
}

.upload-section {
  background-color: var(--card-bg);
  border-radius: 0.75rem;
  padding: 2rem;
  box-shadow: var(--shadow);
  margin-bottom: 2rem;
}

.upload-section h2 {
  font-size: 1.5rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.description {
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
}

#upload-form {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.file-input-wrapper {
  position: relative;
}

.file-label {
  display: block;
  padding: 3rem 2rem;
  border: 2px dashed var(--border-color);
  border-radius: 0.5rem;
  text-align: center;
  cursor: pointer;
  transition: all 0.2s;
  background-color: var(--bg-color);
}

.file-label:hover {
  border-color: var(--primary-color);
  background-color: #f5f3ff;
}

.file-label.drag-over {
  border-color: var(--primary-color);
  background-color: #f5f3ff;
  transform: scale(1.02);
}

.file-label-text {
  display: block;
  font-size: 1rem;
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
}

.file-name {
  display: block;
  font-size: 0.875rem;
  color: var(--text-primary);
  font-weight: 500;
  margin-top: 0.5rem;
}

#file-input {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

.options-wrapper {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.option-group {
  flex: 1;
  min-width: 200px;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

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

.option-group select {
  padding: 0.75rem;
  border: 1px solid var(--border-color);
  border-radius: 0.5rem;
  font-size: 1rem;
  color: var(--text-primary);
  background-color: var(--card-bg);
  cursor: pointer;
  transition: all 0.2s;
}

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

.option-group select:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

.btn-upload {
  background-color: var(--primary-color);
  color: white;
  border: none;
  border-radius: 0.5rem;
  padding: 1rem 2rem;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
  box-shadow: var(--shadow);
}

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

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

.btn-upload:disabled {
  background-color: var(--text-secondary);
  cursor: not-allowed;
  transform: none;
}

.btn-loading {
  display: none;
}

.btn-upload.loading .btn-text {
  display: none;
}

.btn-upload.loading .btn-loading {
  display: inline;
}

.result-section {
  background-color: var(--card-bg);
  border-radius: 0.75rem;
  padding: 2rem;
  box-shadow: var(--shadow);
  display: none;
}

.result-section:not(:empty) {
  display: block;
}

.success-message {
  padding: 1.5rem;
  background-color: #d1fae5;
  border: 1px solid var(--success-color);
  border-radius: 0.5rem;
  margin-bottom: 1rem;
}

.success-message h3 {
  color: var(--success-color);
  font-size: 1.25rem;
  margin-bottom: 0.5rem;
}

.error-message {
  padding: 1.5rem;
  background-color: #fee2e2;
  border: 1px solid var(--error-color);
  border-radius: 0.5rem;
  margin-bottom: 1rem;
}

.error-message h3 {
  color: var(--error-color);
  font-size: 1.25rem;
  margin-bottom: 0.5rem;
}

.download-link {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  background-color: var(--primary-color);
  color: white;
  text-decoration: none;
  border-radius: 0.5rem;
  font-weight: 600;
  transition: all 0.2s;
  margin-top: 1rem;
}

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

.copy-btn {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  background-color: var(--text-secondary);
  color: white;
  border: none;
  border-radius: 0.5rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
  margin-left: 0.5rem;
}

.copy-btn:hover {
  background-color: #4b5563;
}

.copy-btn.copied {
  background-color: var(--success-color);
}

footer {
  background-color: var(--card-bg);
  border-top: 1px solid var(--border-color);
  padding: 2rem 0;
  text-align: center;
  margin-top: auto;
}

footer p {
  color: var(--text-secondary);
  font-size: 0.875rem;
}

.loading-spinner {
  display: inline-block;
  width: 1rem;
  height: 1rem;
  border: 2px solid rgba(255, 255, 255, 0.3);
  border-radius: 50%;
  border-top-color: white;
  animation: spin 0.8s linear infinite;
  margin-right: 0.5rem;
}

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

@media (max-width: 640px) {
  .container {
    padding: 0 1rem;
  }

  header h1 {
    font-size: 1.5rem;
  }

  .upload-section,
  .result-section {
    padding: 1.5rem;
  }

  .file-label {
    padding: 2rem 1rem;
  }

  .options-wrapper {
    flex-direction: column;
  }

  .option-group {
    min-width: 100%;
  }

  .btn-upload {
    width: 100%;
  }

  .download-link,
  .copy-btn {
    display: block;
    width: 100%;
    margin: 0.5rem 0;
    text-align: center;
  }
}