title: CSS - Flexbox div match height of another div
body: <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>.d1 {
    display: flex;
  }
  
  .d2 {
    flex: 1;
    display: flex;
    flex-direction: column;
  }
  
  .d3 {
    background-color: lightblue;
    margin: 5px;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div class="d1"&gt;
    &lt;div class="d2"&gt;
      &lt;div class="d3"&gt;Test1&lt;/div&gt;
      &lt;div class="d3"&gt;Test2&lt;/div&gt;
    &lt;/div&gt;
    &lt;div class="d2"&gt;
      &lt;div class="d3"&gt;Test3&lt;/div&gt;
      &lt;div class="d3"&gt;Test4&lt;br&gt;Test4&lt;/div&gt;
    &lt;/div&gt;
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>In the above code, I have two columns of the same width and 2 <code>div</code>s in each one. But the 4th <code>div</code>, where <code>Test4&lt;br&gt;Test4</code> is written, is as a result higher than the others. How can I make the 2nd <code>div</code>'s height to always match the 4th? Ty</p>
  
  <p><a href="https://i.stack.imgur.com/BYSqb.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/BYSqb.png" alt="enter image description here"></a></p>