<h1>FAQ</h1>

<details role="group">
  <summary role="button" aria-expanded="false"><strong>hoge?</strong></summary>
  <p>hogehogehogehoge
    hogehogehogehogehoge
    hogehogehogehogehoge
    hogehogehogehogehoge
    hogehogehogehoge
    hogehogehogehogehoge
    hogehogehogehogehoge
    hogehogehogehogehoge
    hogehogehogehoge
    hogehogehogehogehoge
    hogehogehogehogehoge
    hogehogehogehogehoge
    hogehogehogehoge
    hogehogehogehogehoge
    hogehogehogehogehoge
    hogehogehogehogehoge
    </p>
</details>
<details role="group">
  <summary role="button" aria-expanded="false"><strong>piyo?</strong></summary>
  <p>piyopiyopiyo
  piyopiyopiyo
  piyopiyopiyo
  piyopiyopiyo
  piyopiyopiyo
  piyopiyopiyo
  piyopiyopiyo
  piyopiyopiyo
  piyopiyopiyo
  piyopiyopiyo
  piyopiyopiyo
  piyopiyopiyo</p>
</details>

body {
  text-align: center;
}

details {
  margin: 2rem auto;
  width: 75%;
}
details p {
  padding: 2rem 5rem;
  line-height: 2;
  font-size: 0.9rem;
  text-align: left;
}

summary {
  display: block;
  outline: none;
}
summary::-webkit-details-marker {
  display: none;
}
summary:before {
  display: inline-block;
  content: "›";
  margin-right: 0.5rem;
  font-weight: bold;
  font-size: 1rem;
  transition: all 300ms ease;
}
summary:hover {
  cursor: pointer;
}

details[open] summary {
  color: red;
  transition: all 300ms ease;
}
details[open] p {
  animation: openDetail 400ms ease;
  background: #f9f9f9;
}
details[open] summary::before {
  transform: rotate(90deg);
}

@keyframes openDetail {
  0% {
    opacity: 0;
    background: white;
    transform: translateY(0%);
  }
  50% {
    transform: translateY(3%);
  }
  100% {
    opacity: 1;
    background: #f9f9f9;
    transform: translateY(0%);
  }
}
Rerun