JSFiddle - React, Tailwind, and code Playground

HTML

<div id="column">    
    <div class="container">
        <div class="event red">            
        </div>
    </div>
    
    <div class="container">
        <div class="event blue">
        </div>
    </div>
    
</div>

CSS

#column {
    width:300px;
    height:500px;
    margin:0 auto;
    background-color:#f9f9f9;
}

.container {
    height:10px;
    background-color:#f0f0f0;
    margin-bottom:125px;
    z-index:1;
}

.event {
    height:300px;
    width:100px;
    z-index:2;
    float:left;
}

.red { background-color:#f00; }
.blue { background-color:#00f; }