:root {
  --primary-color: #4361ee;
  --secondary-color: #3f37c9;
  --accent-color: #4895ef;
  --light-color: #f8f9fa;
  --dark-color: #212529;
}

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background-color: #f5f7fa;
  color: var(--dark-color);
  line-height: 1.6;
}

.app-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 2rem 1rem;
}

.header {
  text-align: center;
  margin-bottom: 2rem;
}

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

.header p {
  color: #6c757d;
  font-size: 1.1rem;
}

.card {
  border-radius: 12px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
  border: none;
  overflow: hidden;
  transition: transform 0.3s ease;
}

.card:hover {
  transform: translateY(-5px);
}

.card-header {
  background-color: var(--primary-color);
  color: white;
  font-weight: 600;
  padding: 1rem;
}

.upload-area {
  border: 2px dashed #dee2e6;
  border-radius: 8px;
  padding: 3rem 2rem;
  text-align: center;
  cursor: pointer;
  transition: all 0.3s ease;
  background-color: #f8f9fa;
}

.upload-area:hover, .upload-area.dragover {
  border-color: var(--primary-color);
  background-color: rgba(67, 97, 238, 0.05);
}

.upload-icon {
  font-size: 3rem;
  color: var(--primary-color);
  margin-bottom: 1rem;
}

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

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

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

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

.progress {
  height: 10px;
  border-radius: 5px;
}

.pdf-info {
  display: flex;
  justify-content: space-between;
  margin-bottom: 1rem;
}

.pdf-info-item {
  text-align: center;
  padding: 0.5rem;
  background-color: #f8f9fa;
  border-radius: 8px;
  flex: 1;
  margin: 0 0.5rem;
}

.pdf-info-item .value {
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--primary-color);
}

.pdf-info-item .label {
  font-size: 0.9rem;
  color: #6c757d;
}

.preview-container {
  margin-top: 2rem;
}

.preview-item {
  margin-bottom: 2rem;
  position: relative;
}

.preview-item canvas {
  width: 100%;
  border-radius: 8px;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.preview-item .page-number {
  position: absolute;
  top: 10px;
  right: 10px;
  background-color: rgba(0, 0, 0, 0.7);
  color: white;
  padding: 0.25rem 0.5rem;
  border-radius: 4px;
  font-size: 0.8rem;
}

.export-options {
  margin-top: 1rem;
  display: flex;
  align-items: center;
}

.export-options .form-check {
  margin-right: 1.5rem;
}

footer {
  text-align: center;
  margin-top: 3rem;
  padding-top: 1rem;
  border-top: 1px solid #dee2e6;
  color: #6c757d;
}

@media (max-width: 768px) {
  .pdf-info {
    flex-direction: column;
  }
  
  .pdf-info-item {
    margin: 0.5rem 0;
  }
  
  .export-options {
    flex-direction: column;
    align-items: flex-start;
  }
  
  .export-options .form-check {
    margin-bottom: 0.5rem;
  }
}

/* 加载动画 */
.spinner {
  width: 40px;
  height: 40px;
  margin: 100px auto;
  background-color: var(--primary-color);
  border-radius: 100%;  
  -webkit-animation: sk-scaleout 1.0s infinite ease-in-out;
  animation: sk-scaleout 1.0s infinite ease-in-out;
}

@-webkit-keyframes sk-scaleout {
  0% { -webkit-transform: scale(0) }
  100% { -webkit-transform: scale(1.0); opacity: 0; }
}

@keyframes sk-scaleout {
  0% { transform: scale(0); -webkit-transform: scale(0); }
  100% { transform: scale(1.0); -webkit-transform: scale(1.0); opacity: 0; }
}