I made a navigation bar for my website with some dropdown at hover content. However, it seems that scrolling is disabled for them and I have tried many ways but failed to enable the scrollbar. Since the dropdown content is quite long I would like the scrollbar to only appear when the resolution or window size is small.
CSS(Not full, I didn't put most the parts regarding the styles):
ul.nav li a {
  display: block;
  color: white;
  text-align: center;
  padding: 16px 16px;
  text-decoration: none;
  font-family: Arial;
  z-index: 5;
}
ul.nav li a:hover:(.active), .dropdown:hover .dropbtn {
  background-color: #760808;
}
.dropdown-content {
  display: none;
  position: absolute;
  background-color: #830303;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.2);
  z-index: 50;
}
.dropdown-content a {
  color: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
  text-align: left;
  z-index: 50;
}<ul class="nav">
  <li><a href="homepage.html">Homepage</a>
  </li>
  <li class="dropdown">
    <a class="active" href="javascript:void(0" class="dropbtn">a</a>
    <div class="dropdown-content">
      <a href="#">Link 1</a><a href="#">Link 2</a>
      <a href="#">Link 3</a></div>
  </li>
  <li class="dropdown">
    <a href="javascript:void(0" class="dropbtn">be</a>
    <div class="dropdown-content">
      <a href="#">Link 1</a>
      <a href="#">Link 2</a>
      <a href="#">Link 3</a>
    </div>
  </li>
  <li class="dropdown">
    <a href="javascript:void(0" class="dropbtn">c</a>
    <div class="dropdown-content">
      <a href="#">Link 1</a>
      <a href="#">Link 2</a>
      <a href="#">Link 3</a>
    </div>
  </li>
  <li><a href="../d.html">d</a></li>
  <li><a href="../e.html">e</a></li>
</ul> 
     
    