JSFiddle - React, Tailwind, and code Playground

by Agony

HTML

<div class='PopupPanelBG'>This is some stuff


    <div class='PopupPanel'>
        <div>
            <div id="innerdiv">some stuff that is really bigsome stuff that is really bigsome stuff that is really bigsome stuff that is really bigsome stuff that is really bigsome stuff that is really big</div>
        </div>
    </div>
</div

CSS

.PopupPanelBG {
	background: rgba(0, 0, 0, 0.7);
	position: fixed;
	left: 0;
	top: 0;
	z-index: 1000;
    width:100%;
    height:100%;
}

.PopupPanel {
    top:40%;
    left:25%;
    position:relative;
}

.PopupPanel>div:first-child {
    top:40%;
    left:25%;
	opacity: 0.9;
	background-color: #e1efbb;
	border: 1px solid gray;
	padding: 8px;
    max-width:50%;
}
#innerdiv{
    top:50%;
    left:50%;
    overflow-x:scroll;
    max-width:100%;
    white-space:nowrap;
}