.accordion {
  margin: 2em 0;
}
.accordion__summary {
  display: block;
  background: #d3d3d3; /* 見出しの背景色 */
  font-weight: bold;
  position: relative;
  list-style: none; /* 矢印を消す */
  cursor: pointer;
  padding: 10px 38px 10px 10px;
}
.accordion__summary::-webkit-details-marker {
  display: none;
}
.accordion__summary::after {
  content: "+";
  font-size: 1.4em; /* 記号のサイズ */
  position: absolute;
  right: 10px;
  top: 50%;
  transform: translateY(-50%);
}
.accordion[open] .accordion__summary::after {
  content: "−";
}
.accordion__detail {
  padding: 4px 10px;
  margin: 10px 0;
}
.accordion__text {
  margin: 0;
}