JSFiddle - React, Tailwind, and code Playground

HTML

<header>Header</header>

<main>
  <div class="row">
    <div class="col container">
      <div class="left">
        <div class="name">
          <strong>Name</strong> BoB Smith</div>
        <div class="address">
          <strong>Address</strong>
          <p>21</p>
          <p>Somewhere Street</p>
          <p>Somewhere City</p>
          <p>That Country</p>
          <P>BWERE EREWW</P>
        </div>
        <div>
          <strong>Something else</strong>
          <ul>
            <li>One</li>
            <li>Two</li>
            <li>Three</li>
            <li>Four</li>
            <li>Five</li>
            <li>Six</li>
            <li>Seven</li>
            <li>Eight</li>
            <li>Nine</li>
            <li>Ten</li>
          </ul>
        </div>
      </div>
      <div class="right">
        <div class="name">
          <strong>Name</strong> BoB Smith</div>
        <div class="address">
          <strong>Address</strong>
          <p>21</p>
          <p>Somewhere Street</p>
        </div>
        <div>
          <strong>Something else</strong>
          <ul>
            <li>One</li>
          </ul>
        </div>
      </div>
    </div>
  </div>
</main>

CSS

* {
  box-sizing: border-box;
}

div,
main {
  border: 1px solid red;
}

body {
  display: flex;
  flex-direction: column;
  margin: 0;
  height: 100vh;
}

main {
  height: 100%;
  flex: 1 1 0;
  display: flex;
}

.row {
  display: flex;
  flex: 1;
}

.col {
  flex-grow: 1;
  flex-shrink: 1;
  flex-basis: 0;
  display: flex;
}

.container {
  display: flex;
  flex: 1;
}

.container {
  display: flex;
}

.container .left,
.container .right {
  flex: 1;
  height: 100%;
  overflow: auto;
}

main .row:first-child {
  height: 100%;
}

.left>div,
.right>div {
  height: 30%;
}