JSFiddle - React, Tailwind, and code Playground

HTML

<div id="outer-container">
    <div id="left">
      <ul>
        <li>1. item</li>
        <li>2. item</li>
        <li>3. item</li>
        <li>4. item</li>
      </ul>
    </div>
    <div id="right">
      Some content inside that is static.
    </div>
  </div>

CSS

#left{
    margin-right: 15px;
    width: 425px;
    background-color:#11DD52;
}

#right{
    width:200px;
    background-color:#4477AA;
}
#left, #right{
  display:table-cell;
}