JSFiddle - React, Tailwind, and code Playground

HTML

<div id="content">
    <div id="fixed">
        1
    </div>
    <div id="elastic">
        2
    </div>
</div>

CSS

* {
    margin:0;
    padding:0;
}
html, body {
    width:100%;
    }
#content
{
    min-width: 1000px;
    height:300px;
    background-color: black;
    position:relative;
}
#elastic
{
    width:100%;
    height:100%;
    background-color: yellow;
    float:right;
    
}
#fixed
{
    position: absolute;
   left:0;
    width:300px;
    height:100%;
    background-color: green;
    
}