JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <div class="a">1a</div>
    <div class="a">2a</div>
    <div class="a">3a</div>
    <div class="b">1b</div>
    <div class="a">4a</div>
    <div class="b">2b</div>
    <div class="b">3b</div>
</div>

CSS

.b ~ .b {
    width:200px;
    background:blue;
    color:#fff;
}
.b ~ .b ~ .b {
    width:auto;
    background:transparent;
    color:#000;
}