JSFiddle - React, Tailwind, and code Playground
HTML
<ul>
<li class="bubble">child 1</li>
<li class="bubble">child 1</li>
<li class="bubble">child 1</li>
<li class="bubble">last child</li>
</ul>
CSS
li.bubble:last-child{
color: red
}
<ul>
<li class="bubble">child 1</li>
<li class="bubble">child 1</li>
<li class="bubble">child 1</li>
<li class="bubble">last child</li>
</ul>
li.bubble:last-child{
color: red
}