JSFiddle - React, Tailwind, and code Playground

HTML

<div class="box">1-1</div>
<div class="box special">2</div>
<div class="box special">3</div>
<div class="box special">4</div>
<div class="box special">5</div>
<div class="box special">6</div>
<div class="box special">7</div>
<div class="box special">8</div>

<div class="box-2">1-2</div>

<div class="box special">2</div>
<div class="box special">3</div>
<div class="box special">4</div>
<div class="box special">5</div>
<div class="box special">6</div>
<div class="box special">7</div>
<div class="box special">8</div>

CSS

.box, .box-2
{
    width: 100px;
    height: 50px;
    background-color: #e3e3e3 !important;
}

.special:nth-child(2n+0)
{
    background-color: red !important;
}
.special:nth-child(2n+3)
{
    background-color: blue !important;
}