JSFiddle - React, Tailwind, and code Playground

HTML

<div class="main">
    <div class="box">a</div>
    <div class="box">b</div>    
    <div class="box" style="height:100px;">c</div>  
</div>

CSS

.main{
    height:auto;
    display:table;
    
}
.box{
    height:100%;
    width:80px;
    display:table-cell;
    background:gray;
    border:1px solid red
}