Why does flexbox stretch my image rather than retaining aspect ratio?
<p>Flexbox has this behaviour where it stretches images to their natural height. In other words, if I have a flexbox container with a child image, and I resize the width of that image, the height doesn't resize at all and the image gets stretched.</p>
<p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
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<pre class="snippet-code-css lang-css prettyprint-override"><code>div {
  display: flex; 
  flex-wrap: wrap;
}

img {
  width: 50%
}</code></pre>
<pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div&gt;
    &lt;img src="https://i.imgur.com/KAthy7g.jpg" &gt;
    &lt;h1&gt;Heading&lt;/h1&gt;
    &lt;p&gt;Paragraph&lt;/p&gt;
&lt;/div&gt;</code></pre>
</div>
</div>
</p>
<p>What causes this?</p>