/* static/style.css */
body {
  font-family: 'Segoe UI', sans-serif;
  background: #f0f2f5;
  text-align: center;
  margin: 0;
  padding: 20px;
}

.container {
  max-width: 500px;
  margin: 0 auto;
  padding: 20px;
  background: white;
  border-radius: 12px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

h1 {
  color: #333;
}

#puzzle {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-gap: 8px;
  margin: 20px auto;
  width: 320px;
  height: 320px;
}

.tile {
  display: flex;
  align-items: center;
  justify-content: center;
  background: #3498db;
  color: white;
  font-size: 24px;
  font-weight: bold;
  border-radius: 8px;
  cursor: pointer;
  user-select: none;
  transition: 0.2s;
}

.tile:hover {
  background: #2980b9;
}

.empty {
  background: #f0f2f5;
  border: 2px dashed #ccc;
  cursor: default;
}

button {
  padding: 10px 20px;
  font-size: 16px;
  background: #2ecc71;
  color: white;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  margin-top: 10px;
}

button:hover {
  background: #27ae60;
}