header {
  background-color: #0056b3;
  color: white;
  padding: 15px 20px;
  position: relative; /* 相対位置指定を追加 */
  margin-bottom: 20px;
}

header h1 {
  text-align: center;
  margin: 0;
}

footer {
  background-color: #0056b3;
  color: white;
  padding: 15px 0;
  width: 100%;
  text-align: center;
}

footer a {
  color: white;
  text-decoration: none;
  margin: 0 10px;
}

#convertBtn {
  display: block;
  margin: 20px auto;
  padding: 10px 20px;
  font-size: 16px;
  background-color: #0056b3;
  color: white;
  border: none;
  border-radius: 4px;
  cursor: pointer;
}
button:disabled {
  background-color: #ccc;
  cursor: not-allowed;
}
#fileInput {
  display: block;
  margin: 20px auto;
}