JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
  <div class="content">
    <div>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Repellat reiciendis, impedit dolor odio deserunt, asperiores incidunt quos magni neque inventore nam, facilis nulla. Quaerat eaque quo obcaecati nihil aliquam sequi?</div>
    <div>Sapiente quam sed, placeat debitis iste perspiciatis in error ad soluta ut cum, quae doloremque, voluptate eius dolor nostrum, minus nam porro. Quasi dicta assumenda veniam quidem, magni optio illo.</div>
  </div>
  <div class="side">
    menu
  </div>
</div>

CSS

.container {
  width: 600px;
  margin: auto;
  background: white;
  overflow: hidden; /* самый простой клирфикс, можете использовать другой*/
}

.content {
  width:400px;
  background: blue;
  border-right:200px solid red;;
  float: left;
}
.side {
  width: 200px;
  margin-left: -200px;
  background: red;
  float: left;
}