JSFiddle - React, Tailwind, and code Playground

HTML

<div id="milestone">
      <div id="milestonecontent">
          <div id="event">
           </div>
      </div>
      <div class="actions">
      </div>
  </div>

CSS

#body{
  background-color: #e9eaed;
}

#milestone{
  width: 512px;
  height: 137px;
  background-color: blue;  
}

#milestonecontent{
  width: 512px;
  height: 104px;
  background-color: green;
  overflow: auto;
}
#event{
  position: relative;
  margin: 10px auto;
  width: 512px;
  height: 58px;
  background-color: red;
 
}
.actions{
  border-top: 1px solid #e9eaed;
  position: relative;
  width: 512px;
  height: 33px;
  background-color: grey;
}