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>
        <li>5. item</li>
        <li>6. item</li>
        <li>7. item</li>
        <li>8. item</li>          
      </ul>
    </div>
    <div id="right">
      Some content inside that is static.
        <div class="clr"></div>
    </div>
  </div>

CSS

#outer-container{
    overflow:hidden;
}
#left{
    margin-right: 15px;
    width: 425px;
    background-color:#11DD52;
    float:left;
}

#right{
    width:200px;
    background-color:#4477AA;
    margin-left:440px;

}
.clr{clear:both;}