In the bootstrap docs eg http://getbootstrap.com/css/#forms the checkbox style is slightly rounded and subtle.
However when I reference the bootstrap 3.3.7 css and use this html
<div class="checkbox">
<label>
<input type="checkbox" id="cancelled">
Cancelled
</label>
</div>
my checkbox looks like the standard ugly HTML checkbox.
The same can be seen here https://codepen.io/mathumatix/pen/dzvQvg. I found this question Why checkbox style is not bootstrap style which states that Bootstrap 3.x does not include styling for checkboxes. If that is so, how is the checkbox styled in the Bootstrap docs? With custom css which is not shown? I also tried using Bootstrap 4 alpha and I still don't get any styling on the checkbox. All my other UI elements have the Bootstrap style. What am I missing?