JSFiddle - React, Tailwind, and code Playground

HTML

<div class="outer">
    <div class="inner">a</div>
</div>


<div class="outer2">
    <div class="inner">a</div>
</div>

CSS

.inner {
    margin: 10px;
}
.outer {
    background-color: blue;
}
.outer2 {
    background-color: blue;
    display: inline-block;
}