body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  background: #f4f4f9;
  color: #333;
}

header {
  background: #4a90e2;
  color: white;
  padding: 1rem;
  text-align: center;
}

main {
  padding: 20px;
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
  max-width: 900px;
  margin: auto;
}

section {
  background: white;
  padding: 20px;
  border-radius: 10px;
  box-shadow: 0 2px 6px rgba(0,0,0,0.1);
}

h2 {
  margin-top: 0;
}

button {
  margin: 5px;
  padding: 8px 15px;
  background: #4a90e2;
  border: none;
  border-radius: 5px;
  color: white;
  cursor: pointer;
}

button:hover {
  background: #357abd;
}

canvas {
  display: block;
  margin-top: 10px;
  max-width: 100%;
  border: 1px solid #ccc;
}

.drop-zone {
  border: 2px dashed #4a90e2;
  padding: 20px;
  text-align: center;
  cursor: pointer;
  color: #4a90e2;
  margin-bottom: 10px;
  border-radius: 8px;
  background: #f9f9ff;
}

.drop-zone.dragover {
  background: #e0ebff;
  border-color: #357abd;
}