JSFiddle - React, Tailwind, and code Playground

HTML

<div id="parent">Im a parent
    <div id="stretchable-div">
        <div class="child">a</div>
        <div class="child">b</div>
        <div class="child">c</div>
        <div class="child">c</div>
        <div class="child">c</div>
        <div class="child">c</div>
        <div class="child">c</div>
    </div>
</div>

CSS

#parent{
    width:50%;
    height:200px; 
    background:red; 
    overflow-x: scroll; 
    overflow-y: hidden;
}

#stretchable-div{
    background:darkblue;
    /* width: 600px; works but don't want to manually size*/
    width: auto;
}

.child {
   background:blue;
   width: 100px;
   height: 150px;
   float:left;
}