_includes/header_custom.html

<style>
/* Style The Dropdown Button */
.dropbtn {
  background-color: #0000ff80;
  color: white;
  padding: 22px;
  width: 100%;
  font-size: 14px;
  border: none;
  cursor: pointer;
}

/* The container <div> - needed to position the dropdown content */
.dropdown {
  position: relative;
  display: inline-block;
}

/* 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 14px;
  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: #0000ff;
}
</style>

<!-- Collect the nav links, forms, and other content for toggling -->
<div class="dropdown" id="apache-navbar" style="float:left;">
  <button class="dropbtn">ASF</button>
  <div class="dropdown-content">
    <a class="dropdown-item" href="https://www.apache.org/">Foundation</a>
    <a class="dropdown-item" href="https://www.apache.org/events/current-event.html">Event</a>
    <a class="dropdown-item" href="https://www.apache.org/licenses/">License</a>
    <a class="dropdown-item" href="https://www.apache.org/foundation/sponsorship.html">Sponsorship</a>
    <a class="dropdown-item" href="https://www.apache.org/security/">Security</a>
    <a class="dropdown-item" href="https://privacy.apache.org/policies/privacy-policy-public.html">Privacy</a>
    <a class="dropdown-item" href="https://www.apache.org/foundation/thanks.html">Thanks</a>
  </div>
</div><!-- /.navbar-collapse -->