JSFiddle - React, Tailwind, and code Playground

HTML

<a class="dropdown-toggle" data-toggle="dropdown" id="alertingDashboardDropdown" href="#">
  <span>Alerts Dashboard</span>
  <span class="pulse">5</span>
</a>

CSS

.pulse {
  display: inline-block;
  width: 22px;
  height: 22px;
  line-height: 22px;
  border-radius: 100%;
  box-shadow: 0 0 0 rgba(204,169,44, 0.4);
  background-color: #cca92c;
  text-align: center;
  cursor: pointer;
  animation: pulse 2s infinite;
}

.pulse:hover {
  animation: none;
}

@keyframes pulse {
  0% {
    box-shadow: 0 0 0 0 rgba(196,33,61, 0.85);
  }
  70% {
    box-shadow: 0 0 0 10px rgba(204,169,44, 0);
  }
  100% {
    box-shadow: 0 0 0 0 rgba(204,169,44, 0);
  }
}