<div class="ac_menu">
  <label for="Panel1">メニュー1</label>
  <input type="radio" name="menu" id="Panel1" class="on-off" />
  <div>
    <p>コンテンツが入ります。</p>
  </div>
  <label for="Panel2">メニュー2</label>
  <input type="radio" name="menu" id="Panel2" class="on-off" />
  <div>
    <p>コンテンツが入ります。</p>
  </div>
  <label for="Panel3">メニュー3</label>
  <input type="radio" name="menu" id="Panel3" class="on-off" />
  <div>
    <p>コンテンツが入ります。</p>
  </div>
</div>
.ac_menu{
  width: 300px;
}

/* メニューの部分 */
.ac_menu label{
  background: #333;
  color: #fff;
  padding: 10px;
  display: block;
  margin: 0;
  border: 1px solid #fff;
  cursor: pointer;
}
.ac_menu input[type="radio"].on-off{
  display: none;
}

/* コンテンツの部分 */
.ac_menu div{
  -webkit-transition: all 0.5s;
  -moz-transition: all 0.5s;
  -ms-transition: all 0.5s;
  -o-transition: all 0.5s;
  transition: all 0.5s;
  margin: 0;
  padding: 0 10px;
  list-style: none;
}
.ac_menu input[type="radio"].on-off + div{
  height: 0;
  overflow: hidden;
}
.ac_menu input[type="radio"].on-off:checked + div{
  height: 100px;
}

External CSS

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External JavaScript

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