JSFiddle - React, Tailwind, and code Playground

HTML

<div id="wrapper">
    <div class="first">first</div>
    <div class="first bb">first second</div>
    <div class="first bb">first second</div>
    <div class="first bb">first second</div> <!-- <- need to select this -->
    <div class="first a">first</div>
    <div class="first a">first</div>
    <div class="first a">first</div>
    <div class="first bb">first second</div>
    <div class="first bb">first second</div>
    <div class="first bb">first second</div>
    <div class="first bb">first second</div> <!-- <- need to select this -->
    <div class="first a">first</div>
    <div class="first a">first</div>
    <div class="first a">first</div>
    <div class="first bb">first second</div> <!-- <- need to select this -->
</div>

CSS

.first.bb:last-child {
        color:red;
    }

     .first.bb + .first.a {
            color:red;
    }