JSFiddle - React, Tailwind, and code Playground

HTML

<div class="groups">
    <div class="group"></div>
    <div class="group"></div>
    <div class="group"></div>
</div>

CSS

.groups .group{
    background-color:#000;
}
.groups .group:first-child{
    background-color:yellow;
}
.groups .group:nth-child(2):nth-last-child(2),
.groups .group:nth-child(2):last-child{
    background-color:red;
}
.groups .group:last-child:nth-child(3){
    background-color:green;
}
.groups{
    height:100px;
    font-size:0;
    line-height:0;
}
.groups .group{
    display:inline-block;
    height:100px;
    width:30px;    
}