Checkbox is not visible on Firefox 74.0 (64-bit) on Ubuntu

When I navigate to sample page with checkbox https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/checkbox

<div>
  <input type="checkbox" id="scales" name="scales"
         checked>
  <label for="scales">Scales</label>
</div>

<div>
  <input type="checkbox" id="horns" name="horns">
  <label for="horns">Horns</label>
</div>

I do not see checkboxes.

Also when I click on label, I can not notice if checkbox is selected or not. This is unlikely to be a bug, I hope it is a problem with some configuration.