JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
    <div id="left">
        <p>left one</p>
        <p>...</p>
    </div>
    <div id="right">right one</div>
</div>

CSS

#container {
    position: relative;
}

#left {
    width: 300px;
    background: red;
}

#right {
    position: absolute;
    left: 300px; 
    right: 0px;
    top: 0px; bottom: 0px;
    background: green;
}