index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <link rel="icon" type="image/svg+xml" href="/vite.svg" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Pulse effect</title>
    <link rel="stylesheet" href="/style.css">
    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css" integrity="sha512-SfTiTlX6kk+qitfevl/7LibUOeJWlt9rbyDn92a1DqWOw9vWG2MFoays0sgObmWazO5BQPiFucnnEAjpAB+/Sw==" crossorigin="anonymous" referrerpolicy="no-referrer" /> 
  </head>
  <body>
    <div class="main">
      <div class="pulse-box">
        <a href="#" class="pulse-pseudo">
          <i class="fa fa-bell"></i>
        </a>
      </div>
      <div class="pulse-box">
        <a href="#" class="pulse-shadow">
          <i class="fa fa-bell"></i>
        </a>
      </div>
    </div>
  </body>
</html>