Not sure if should post here for a minor thing I noticed (sorry for the flood):
The look of the radio buttons is a bit different than the checkboxes. The gray color is a bit pale. When used in a form it even looks disabled compared to other elements. Same for the circle and the label.
See a screenshot:
Code example:
<label> <input type="radio" name="order" value="popularity"> <span>Popularity</span> </label>