details {
    margin-bottom: 20px;
    border: solid 2px #1566f3;
  }
  summary {
    list-style: none; /* ?を非表示 */
    color:#fa3807;
    position: relative;
    padding: 10px 35px 10px 20px;
  }
  summary::-webkit-details-marker {
    display: none;
  }
  summary::before {
    content: "";
    width: 14px;
    height: 0;
    border-top: solid 2px #1566f3;
    position: absolute;
    top: 50%;
    right: 20px;
    transform: translateY(-50%);
  }
  summary::after {
    content: "";
    width: 0;
    height: 14px;
    border-right: solid 2px #1566f3;
    position: absolute;
    top: 50%;
    right: 26px;
    transform: translateY(-50%);
  }
  details[open] summary::after {
    opacity: 0;
  }
  .details_content {
    padding: 0 20px 10px;
  }