accordion/index.html

<!doctype html>
<html lang="ru">

<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
  <title>Accordion</title>
  <style>
    body {
      margin: 0;
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji";
      font-size: 1rem;
      font-weight: 400;
      line-height: 1.5;
      color: #212529;
      text-align: left;
      background-color: #fff;
    }

    *,
    *::before,
    *::after {
      box-sizing: border-box;
    }
  </style>
  <link href="css/accordion.css" rel="stylesheet">
  <script src="js/accordion.js"></script>
</head>

<body>


  <div class="accordion" style="max-width: 30rem; margin: 1rem auto 2rem;">
    <div class="accordion__item accordion__item_show">
      <div class="accordion__header">
        Заголовок 1
      </div>
      <div class="accordion__body">
        Lorem ipsum dolor, sit amet consectetur adipisicing elit. Tenetur et numquam optio, aut consequuntur iure magni
        tempore quo, velit, quos ipsum perferendis sit quidem sapiente voluptatem nesciunt rerum soluta amet.
      </div>
    </div>
    <div class="accordion__item">
      <div class="accordion__header">
        Заголовок 2
      </div>
      <div class="accordion__body">
        Lorem ipsum dolor sit amet consectetur adipisicing elit. Non earum deleniti recusandae placeat rem eius quod
        aliquid adipisci nemo alias debitis corporis pariatur quibusdam est, porro fuga id iure vero?
      </div>
    </div>
    <div class="accordion__item">
      <div class="accordion__header">
        Заголовок 3
      </div>
      <div class="accordion__body">
        Lorem ipsum dolor sit amet consectetur, adipisicing elit. Aliquid repellat dicta vel sapiente laudantium minima
        porro voluptatem nam, alias aliquam qui quasi eveniet odit fugiat eius aspernatur nesciunt veniam expedita!
      </div>
    </div>
  </div>

  <script>
    new ItcAccordion(document.querySelector('.accordion'), {
      alwaysOpen: true
    });
  </script>

</body>

</html>