body {
    font-family: Arial, sans-serif;
    margin: 20px;
  }
  
  h1 {
    text-align: center;
  }
  
  .muscle-group {
    margin-bottom: 20px;
  }
  
  .muscle-row {
    display: flex;
    align-items: center;
  }
  
  .muscle-row button {
    padding: 10px 20px;
    font-size: 16px;
    cursor: pointer;
    flex-shrink: 0;
    width: 80px; /* ボタンの幅を統一 */
  }
  
  .muscle-row span {
    font-size: 18px;
    margin-left: 10px;
    width: 60px;
    text-align: center;
  }
  
  .muscle-row .progress-bar {
    flex-grow: 1;
    background-color: #e0e0e0;
    height: 24px;
    border-radius: 12px;
    overflow: hidden;
    margin-left: 10px;
    margin-right: 10px; /* レベル表示との間にスペースを追加 */
  }
  
  .bar {
    height: 100%;
    width: 0%;
    background-color: #76c7c0;
    transition: width 0.3s ease;
  }
  
  button#resetButton {
    display: block;
    margin: 30px auto 0 auto;
    padding: 10px 20px;
    font-size: 16px;
    cursor: pointer;
  }