form {
  max-width: 600px;
  margin: 20px auto;
  background: #ffffff;
  padding: 20px;
  border-radius: 12px;
  box-shadow: 0 4px 10px rgba(0,0,0,0.1);
}

input, select, textarea {
  width: 90%;
  padding: 10px;
  margin: 10px 0;
  border-radius: 8px;
  border: 1px solid #ccc;
  font-size: 16px;
  box-sizing: border-box;
}

button {
  background-color: #1e90ff;
  color: white;
  border: none;
  padding: 10px 16px;
  margin: 10px 5px;
  border-radius: 8px;
  cursor: pointer;
  font-size: 16px;
}

button:hover {
  background-color: #0d70d4;
}

canvas {
  display: block;
  margin: 20px auto;
  max-width: 100%;
  height: auto;
  border: 2px solid #ddd;
  border-radius: 8px;
}

.background-selector {
  margin: 20px 0;
  font-family: sans-serif;
}

.background-selector h3 {
  font-size: 16px;
  margin-bottom: 10px;
}

.background-options {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.bg-option {
  display: flex;
  flex-direction: column;
  align-items: center;
  cursor: pointer;
  border: 2px solid transparent;
  border-radius: 8px;
  padding: 4px;
  transition: border-color 0.3s;
}

.bg-option input[type="radio"] {
  display: none;
}

.bg-option img {
  width: 100px;
  height: auto;
  border-radius: 6px;
  box-shadow: 0 0 4px rgba(0, 0, 0, 0.2);
}

.bg-option input[type="radio"]:checked + img {
  border: 3px solid #007BFF;
  box-shadow: 0 0 8px rgba(0, 123, 255, 0.6);
}

/* モバイル対応 */
@media (max-width: 600px) {
  input, textarea, select, button {
    width: 100%;
    margin: 8px 0;
  }

  form {
    padding: 15px;
  }
}