index.html

<!doctype html>
<html lang="ru">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Выпадающие списки</title>
    <link rel="stylesheet" href="./style.css">    
</head>
<body>
    
    <main class="content">
        <div class="dropdown">
            <div class="dropdown__value">JavaScript</div>
            <ul class="dropdown__list">
                <li class="dropdown__item">
                    <a href="" class="dropdown__link">
                        JavaScript
                    </a>
                </li>
                <li class="dropdown__item">
                    <a href="" class="dropdown__link">
                        PHP
                    </a>
                </li>
                <li class="dropdown__item">
                    <a href="" class="dropdown__link">
                        Python
                    </a>
                </li>
                <li class="dropdown__item">
                    <a href="" class="dropdown__link">
                        Fortran
                    </a>
                </li>
            </ul>
        </div>
    </main>
    
    <script src="./app.js"></script>
</body>
</html>