JSFiddle - React, Tailwind, and code Playground

HTML

<div class="row-wrapper">
    <div class="col-wrapper-outer">
      <div class="arrow-wrapper">
        &darr;
      </div>
      <div class="col-wrapper">
        <div class="header">Please align tops.</div>
        <div class="contents">Let me grow.</div>
      </div>
    </div>
    <div class="col-wrapper-outer">
      <div class="arrow-wrapper">
        &darr;
      </div>
      <div class="col-wrapper">
        <div class="header">please align tops.</div>
        <div class="contents">Let me grow.<br>Please<br>align<br>bottoms.</div>
      </div>
    </div>
  </div>

CSS

.row-wrapper {
    display: flex;
  }
  .col-wrapper-outer {
    display: flex;
    flex-wrap: wrap;
  }
  .arrow-wrapper {
    width: 100%;
    text-align: center;
    font-size: 30px;
  }
  .col-wrapper {
    width: 100%;
    display: flex;
    flex-direction: column;
    border: 2px solid red;
    color: white;
  }
  .col-wrapper .header {
    background: blue;
  }
  .col-wrapper .contents {
    flex: 1 0 auto;
    background: green;
  }