JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
    <div id="div1">
        <img src="//dummyimage.com/3000" />
    </div>
    <div id="div2">300</div>
</div>

CSS

div {
    border: 1px solid red;
}
#container {
    max-width: 1000px;
    display: flex;
}
#div1 {
    flex: 1 1 100%;
    min-width: 0;
}
#div1 img {
    max-width: 100%;
}
#div2 {
    width: 300px;
    flex: 0 0 auto;
}