Script

var toggle = new Toggle({
  blur: true,
  buttonClass: 'toggle-btn',
  buttonClassExpanded: 'toggle-btn-active',
  parentClass: 'toggle-parent'
})

HTML

<button>
  Choose a Dessert
  <i class="fa fa-angle-down" aria-hidden="true"></i>
</button>

<nav class="toggle">
  <ul>
    <li><a href="#">Pie</a></li>
    <li><a href="#">Cake</a></li>
    <li><a href="#">Ice Cream</a></li>
  </ul>
</nav>

CSS

/* Hide collapsed */
[aria-expanded="false"] {
  display: none;
}

/* Menu position */
.toggle-parent {
  position: relative;
}
.toggle {
  left: 0;
  position: absolute;
  top: 100%;
  width: 100%;
}

/* Flip the icon */
.toggle-btn i {
  transition: transform 0.3s ease;
}
.toggle-btn-active i {
  transform: rotate(180deg);
}