JSFiddle - React, Tailwind, and code Playground

HTML

<ul id="Grid">
        <li></li> <li></li> <li></li> <li></li> <li class="break"></li>
</ul>

CSS

#Grid{
    text-align: justify;
    font-size: 0.1px; /*hide whitespace between elements*/
    width: 400px;
    border: 1px solid black;
    margin-left: none;
    margin: 0;
    padding: 0;
}
 
#Grid li{
    display: inline-block;
    width: 100%;
    height: 10px;
    background-color: red;
    border-right: 3px green solid;
}
 
#Grid .break{
    width: 100%;
    height: 0;
    ...
}