JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css">
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script>
<nav class="navbar navbar-expand-lg navbar-dark bg-dark">
    <a class="navbar-brand" href="#">Tasks</a>

    <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>
    </button>

    <div class="collapse navbar-collapse" id="navbarSupportedContent">
      <ul class="navbar-nav">
        <li class="nav-item dropdown dropdown-notifications open">
        <a href="#notifications-panel" class="nav-link dropdown-toggle" data-toggle="dropdown">
          <i data-count="2" class="oi oi-bell notification-icon" aria-label="Nofitication centre"></i>
        </a>

        <div class="dropdown-container">
         <div class="dropdown-toolbar">
            <div class="dropdown-toolbar-actions">
              <a href="#"><i class="glyphicon glyphicon-search"></i> View All</a>
            </div>
            <h3 class="dropdown-toolbar-title">Recent (3)</h3>
          </div><!-- /dropdown-toolbar -->

          <ul class="dropdown-menu notifications">
            <li class="notification">
                <div class="media">
                  <img data-src="holder.js/50x50?bg=cccccc" class="mr-2 img-circle" alt="50x50"...

CSS

.notifications {
  list-style: none;
  padding: 0; }

.notification {
  display: block;
  padding: 0.8em;
  border-width: 0 0 1px 0;
  border-style: solid;
  border-color: #e9ecef;
  background-color: #ffffff;
  color: #212529;
  text-decoration: none; }
  .notification:last-child {
    border-bottom: 0;
    border-radius: 0 0 0.25rem 0.25rem; }
  .notification:hover, .notification.active:hover {
    background-color: #f9f9f9;
    border-color: #dee2e6;
    text-decoration: none; }
  .notification.active {
    background-color: #efefef; }

.notification-title {
  font-size: 1em;
  margin-bottom: 0; }

.notification-desc {
  margin-bottom: 0;
  font-size: 0.94em; }

.notification-meta {
  color: #868e96; }

.dropdown-notifications > .dropdown-container,
.dropdown-notifications > .dropdown-menu {
  width: 450px;
  max-width: 450px; }

.dropdown-notifications > .dropdown-container {
  margin-top: 0.6rem; }

.dropdown-notifications .dropdown-menu {
  padding: 0; }

.dropdown-notifications .dropdown-toolbar,
.dropdown-notifications .dropdown-footer {
  padding: 0.8em; }

.dropdown-notifications .dropdown-toolbar {
  background: #ffffff; }

.dropdown-notifications .dropdown-footer {
  background: #ced4da; }

.dropdown-notifications .dropdown-toggle::after {
  display: none; }

.navbar .dropdown-notifications .dropdown-menu {
  position: static; }

.notification-icon {
  margin-right: 0.49125rem;
  vertical-align: middle; }

.notification-icon:after {
  position: absolute;
  content: attr(data-count);
  margin-left: -0.49125rem;
  margin-top: -0.49125rem;
  padding: 0 4px;
  min-width: 0.9825rem;
  height: 0.9825rem;
  line-height: 0.9825rem;
  background: red;
  border-radius: 10px;
  color: #ffffff;
  text-align: center;
  vertical-align: middle;
  font-size: 0.786rem;
  font-weight: 600;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; }

.notification...