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                <html lang="ja">
<meta charset="UTF-8">
<link rel="stylesheet" href="styles.css">

<details class="accordion">
  <summary class="accordion-header">セクション 1</summary>
  <div class="accordion-content">

<details class="accordion">
  <summary class="accordion-header">セクション 2</summary>
  <div class="accordion-content">

<details class="accordion">
  <summary class="accordion-header">セクション 3</summary>
  <div class="accordion-content">



                /* アコーディオン全体のスタイリング */
.accordion {
  border: 1px solid #ddd;
  border-radius: 5px;
  margin-bottom: 10px;

/* アコーディオンのヘッダー部分のスタイリング */
.accordion-header {
  padding: 10px;
  background-color: #f7f7f7;
  cursor: pointer;
  outline: none;
  font-weight: bold;
  border-bottom: 1px solid #ddd;
  /* 矢印を消すための追加スタイル */
  list-style: none;

/* アコーディオンのコンテンツ部分のスタイリング */
.accordion-content {
  padding: 15px;
  line-height: 1.5;
  background-color: #fff;

/* アコーディオンが開いている時のヘッダー部分のスタイル */
.accordion[open] .accordion-header {
  background-color: #e7e7e7;

/* アコーディオンの矢印を非表示にするためのスタイリング */
.accordion .accordion-header::-webkit-details-marker {
  display: none;

.accordion .accordion-header::before {
  content: '';

/* 以下のセレクタは将来的な互換性のためには必要ありませんが、
   古いブラウザでは有効な場合があるので記述しています */
.accordion .accordion-header::-moz-list-bullet {
  display: none;