JSFiddle - React, Tailwind, and code Playground

HTML

<div class="outer"><div class="left">left</div><div class="right">right</div></div>

CSS

.outer {
	width: 100%;
	border: 1px solid black;
}
.left, .right {
    display:inline-block;
}
.left {
	min-width: 200px;
	width: 25%;
	background-color: #dcc2c2;

}
.right {
    width:75%;
    max-width:calc(100% - 200px);
	background-color: #d0dee8;

}