JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <span class="yellow">Span 1</span>
    <span class="blue">Span 2</span>
</div>

CSS

.container {
    border: 1px solid black;
    background-color: red;
}

.yellow {
    background-color: yellow;
    border: 1px solid black;
    padding: 10px;
    margin: 0;
}

.blue {
    background-color: blue;
    border: 10px solid black;
    margin: 0;
}