Bootstrap 5 dropdown is defined as
<div class="btn-group">
<button type="button" class="btn btn-danger dropdown-toggle" data-bs-toggle="dropdown" aria-expanded="false">
Action
</button>
<ul class="dropdown-menu">
<li><a class="dropdown-item" href="#"><u>A</u>ction</a></li>
<li><a class="dropdown-item" href="#">A<u>n</u>other action</a></li>
<li><a class="dropdown-item" href="#"><u>S</u>omething else here</a></li>
<li><hr class="dropdown-divider"></li>
<li><a class="dropdown-item" href="#">S<u>e</u>parated link</a></li>
</ul>
</div>
https://jsfiddle.net/b6or2s5e/
If clicked in Action button, first menu item Action is not active (highlighted):
Pressing down arrow is required to activate it:
How to fix it so that opening dropdown highlights first item like in normal windows desktop application menus?