body {
  font-family: sans-serif;
  margin: 20px;
  padding: 0;
  background-color: #f9f9f9;
}

h1 {
  text-align: center;
  font-size: 1.8em;
  color: #333;
  margin-bottom: 20px;
}

form {
  max-width: 600px;
  margin: 0 auto;
  background: white;
  padding: 20px;
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

label {
  display: block;
  margin-top: 16px;
  font-weight: bold;
  color: #444;
}

input[type="text"],
input[type="email"],
textarea {
  width: 100%;
  padding: 10px;
  margin-top: 6px;
  border: 1px solid #ccc;
  border-radius: 4px;
  box-sizing: border-box;
  font-size: 1em;
}

textarea {
  resize: vertical;
}

button {
  margin-top: 20px;
  background-color: #0078d7;
  color: white;
  border: none;
  padding: 12px 20px;
  border-radius: 4px;
  font-size: 1em;
  cursor: pointer;
}

button:hover {
  background-color: #005fa3;
}

.required {
  background-color: red;
  color: white;
  font-size: 0.75em;
  padding: 2px 6px;
  border-radius: 4px;
  margin-left: 6px;
}

.hidden-field {
  position: absolute;
  left: -9999px;
  height: 0;
  overflow: hidden;
}

/* レスポンシブ対応 */
@media (max-width: 600px) {
  body {
    margin: 10px;
  }

  form {
    padding: 15px;
  }

  button {
    width: 100%;
  }
}