title: Styling default validation tooltip
body: <p>Is it possible to style the default tooltip? Here's a <a href="https://jsfiddle.net/yccgyq3y/" rel="noreferrer">JSFiddle</a>  demonstrating the default tooltip.</p>
  
  <pre><code>&lt;form&gt;
      &lt;input type="text" placeholder="Submit without entering value" required&gt;
      &lt;input type="submit"&gt;
  &lt;/form&gt;
  </code></pre>