JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
      <div id="box">
        Floated element
    </div>    
    
    <div class="unfloated">
        element
    </div>  
  
      <div class="unfloated">
        element
    </div>    
          <div class="unfloated">
        element
    </div>    
    
</div>

CSS

.container {
    border: green 1px solid;
    width: 300px;
    overflow: auto;
}

#box {
    float:left;
    border: 1px red solid;
    width:100px;
    height:40px;

}

.unfloated {
    border: blue 1px solid;
    width: 100%;
    height: 30px;
    display: inline-block;
}