Tailwind CSS class .right-0 / .right-*

<div class="relative h-16 w-16 bg-gray-400 m-2">
  <div class="absolute right-0 h-full w-4 bg-teal-400"></div>
</div>
<div class="relative h-16 w-16 bg-gray-400 m-2">
  <div class="absolute right-auto left-0 h-full w-4 bg-teal-400"></div>
</div>

.right-0 { right: 0; }
.right-auto { right: auto; }