JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
    <div id="esquerdo"></div>
    <div id="direito"></div>
</div>

CSS

#container {
    border: #000000 solid 5px;
    margin-top: 10px;
    margin-bottom: 10px;
    width: 90%;
    position: inherit;
    background-color: #eff2ff;
    display: flex;
}
#esquerdo {
    vertical-align: top;
    flex-grow: 1;
    height: 100px;
    background-color: red;
    display: inline-block;
}
#direito {
    vertical-align: top;
    width: 50px;
    height: 100px;
    background-color: yellow;
    display: inline-block;
}