JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
        <div class="right">
            right content fixed width
        </div>
        <div class="left">
            left content flexible width
        </div>
    </div>

CSS

.container {
   height: auto;
   overflow: hidden;
}
    
.right {
    width: 180px;
    float: right;
    background: #aafed6;
}

.left {
    float: none; /* not needed, just for clarification */
    background: #e8f6fe;
    /* the next props are meant to keep this block independent from the other floated one */
    width: auto;
    overflow: hidden;
}