full screen popup html

1<div id="myNav" class="overlay">
2
3  <!-- Button to close the overlay navigation -->
4  <a href="javascript:void(0)" class="closebtn" onclick="closeNav()">&times;</a>
5
6  <!-- Overlay content -->
7  <div class="overlay-content">
8    <a href="#">About</a>
9    <a href="#">Services</a>
10    <a href="#">Clients</a>
11    <a href="#">Contact</a>
12  </div>
13
14</div>
15<span onclick="openNav()">open</span>