JSFiddle - React, Tailwind, and code Playground

HTML

<div class="page-container">
    <div class="side panel">
        <div class="scroll">
            asdfasdf <br> asdfasdf <br>
            asdfasdf <br> asdfasdf <br>
            asdfasdf <br> asdfasdf <br>
            asdfasdf <br> asdfasdf <br>
            asdfasdf <br> asdfasdf <br>
            asdfasdf <br> asdfasdf <br>
            asdfasdf <br> asdfasdf <br>
            asdfasdf <br> asdfasdf <br>
            asdfasdf <br> asdfasdf <br>
            asdfasdf <br> asdfasdf <br>
            asdfasdf <br> asdfasdf <br>
            asdfasdf <br> asdfasdf <br>
            asdfasdf <br> asdfasdf <br>
            asdfasdf <br> asdfasdf <br>
            asdfasdf <br> asdfasdf <br>
            asdfasdf <br> asdfasdf <br>
            asdfasdf <br> asdfasdf <br>
        </div>
    </div>
    <div class="main panel">
        <div class="scroll">
            asdfasdf <br> asdfasdf <br>           
            asdfasdf <br> asdfasdf <br>
        </div>
    </div>
</div>

SCSS

html, body {
    top: 0; bottom: 0; height: 100%;
    left: 0; right: 0;  width: 100%;
    overflow: hidden;
}
.page-container {   
     height: 100%;
     width: 100%;   
    display: table;
}
.panel {
    display: table-cell;
    vertical-align: top;
    min-height: 100%;
}
.panel .scroll {
    display: block;
    overflow-y: scroll;
    height: inherit;
    
    background: gray;
}
.side.panel {
    width: 200px;
}


/*** TO HELP DEBUG ***/
* {
    outline: 1px solid red;
    outline-offset: -1px;
}

JavaScript

function setHeight() {
    $('.panel').height( $(window).height() );
}

$(window)
    .load(setHeight)
    .resize(setHeight);