/* ボタンの指定 */
.js-backToTop{
      position: fixed;
      right: 20px;
      bottom: 40px;
      width: 50px;
      height: 50px;
      /* background: #ffb1b1;
      color: #ee1818; */
      border: none;
      border-radius: 50%;
      font-size: 20px;
      opacity: 0;
      visibility: hidden;
      z-index: 1000;
      transition: 0.3s;
      display: flex;
      align-items: center;
      justify-content: center;
      cursor: pointer;
    }

    .js-backToTop.is-active {
      opacity: 1;
      visibility: visible;
    }