How To Work Hoverable Dropdown ? 
<!-- Css Code Start-->
<style>
.dropbtn {
  background-color: blue;
  color: white;
  padding: 16px;
  font-size: 16px;
  border: none;
}

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

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

.dropdown-content a {
  color: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
  transition:0.5s;
}

.dropdown-content a:hover {
background-color: red;
box-shadow: 1px 2px 5px 2px rgba(23, 23, 23, 0.93);
transition:0.5s;
}

.dropdown:hover .dropdown-content {
display: block;
box-shadow: 1px 2px 5px 2px rgba(23, 23, 23, 0.93);
transition:0.5s;
}

.dropdown:hover .dropbtn {
background-color: black;
box-shadow: 1px 2px 5px 2px rgba(23, 23, 23, 0.93);
}
</style>
 <!-- Css Code End-->

Html Code :
<!--html code start-->
<div class="dropdown">
  <button class="dropbtn">Dropdown</button>
  <div class="dropdown-content">
    <a href="#">Link 1</a>
    <a href="#">Link 2</a>
    <a href="#">Link 3</a>
  </div>
</div>

<!--html code end-->