JSFiddle - React, Tailwind, and code Playground
HTML
<ul>
<li data-heading>1 a</li>
<li>1</li>
<li>1</li>
<li>1</li>
<li data-heading>2 a</li>
<li>1</li>
<li>1</li>
</ul>
CSS
li[data-heading]~ li:not([data-heading]):nth-child(2){
color: blue;
background-color: yellow;
}