* {
  box-sizing: border-box;
}

body {
  font-family: Arial, sans-serif;
  background: #f8f9fa;
  margin: 0;
  padding: 0;
}

.container {
  max-width: 900px;
  margin: 40px auto;
  background: #fff;
  padding: 25px;
  border-radius: 10px;
  box-shadow: 0 0 15px rgba(0,0,0,0.1);
  text-align: center;
}

h1 {
  margin-bottom: 10px;
  color: #333;
}

.upload-box {
  border: 2px dashed #bbb;
  border-radius: 10px;
  padding: 30px;
  background: #fafafa;
  cursor: pointer;
  margin-bottom: 20px;
}

.upload-box:hover {
  border-color: #007bff;
}

.preview-container {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
  gap: 15px;
  margin-top: 20px;
}

.page-preview {
  border: 1px solid #ddd;
  border-radius: 5px;
  padding: 5px;
  background: #fff;
  position: relative;
}

.page-preview canvas {
  max-width: 100%;
  border-radius: 4px;
}

.page-preview input[type="checkbox"] {
  position: absolute;
  top: 5px;
  left: 5px;
  transform: scale(1.3);
}

.buttons {
  margin-top: 20px;
}

button {
  padding: 10px 20px;
  margin: 5px;
  background: #007bff;
  color: #fff;
  border: none;
  border-radius: 6px;
  cursor: pointer;
}

button:disabled {
  background: #ccc;
  cursor: not-allowed;
}

button:hover:enabled {
  background: #0056b3;
}