HTML

<!DOCTYPE html>
<html lang="en">

<head>
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
    <script src="button.js"></script>
    <link rel="stylesheet" href="https://fonts.googleapis.com/icon?family=Material+Icons">
    <link rel="stylesheet" href="https://code.getmdl.io/1.3.0/material.indigo-pink.min.css">
    <script defer src="https://code.getmdl.io/1.3.0/material.min.js"></script>

</head>
<body>
<script>
/* Style The Dropdown Button */

body {
  position: relative;
}

.dropbtn {
  background-color: #4CAF50;
  color: white;
  padding: 16px;
  font-size: 16px;
  border: none;
  cursor: pointer;
}


/* The container <div> - needed to position the dropdown content */

.dropdown {
  position: relative;
  display: inline-block;
  z-index: 0;
}


/* Dropdown Content (Hidden by Default) */

.dropdown-content {
  display: none;
  position: absolute;
  background-color: #f9f9f9;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.2);
  z-index: 1;
}


/* Links inside the dropdown */

.dropdown-content a {
  color: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
}


/* Change color of dropdown links on hover */

.dropdown-content a:hover {
  background-color: #f1f1f1
}


/* Show the dropdown menu on hover */

.dropdown:hover .dropdown-content {
  display: block;
}


/* Change the background color of the dropdown button when the dropdown content is shown */

.dropdown:hover .dropbtn {
  background-color: #3e8e41;
}

.demo-card-wide.mdl-card {
  width: 512px;
  display: none;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

.demo-card-wide>.mdl-card__title {
  color: #fff;
  height: 176px;
  background: url('https://www.tes.com/sites/default/files/maths_blackboard.jpg') center / cover;
}

.demo-card-wide>.mdl-card__menu {
  color: #fff;
}


.background-mask {
  display: none;
  position: absolute;
  width: 100vw;
  height: 100vh;
  top: 0;
  left: 0;
  background-color: rgba(0, 0, 0, 0.7);
}


<div class="dropdown">
  <button class="dropbtn">Compulsary</button>

 </script>
  <div class="dropdown-content">
    <a href="#" data-content="English Language Content">English Language</a>
    <a href="#" data-content="English Literature Content">English Literature</a>
    <a href="#" data-content="Mathematics Content">Mathematics</a>
  </div>
</div>

<div class="background-mask"></div>

<div class="demo-card-wide mdl-card mdl-shadow--2dp">
  <div class="mdl-card__title">
    <h2 class="mdl-card__title-text">Mathematics</h2>
  </div>
  <div class="mdl-card__supporting-text">
    This is one of the compulsary subjects and is crucial. It involves geometry, algebra, data, and numbers.
  </div>
  <div class="mdl-card__actions mdl-card--border">
    <a class="mdl-button mdl-button--colored mdl-js-button mdl-js-ripple-effect">
      Done
    </a>
  </div>
</div>

</body>
</html>