Check box image wrongly positioned

It seems that some JS code is adding an image over the checkbox and hiding the original checkbox:

input.form-checkbox,
input.form-radio {
  opacity: 0;
  width: 20px;
  height: 20px;
}

The problem is that the new checkbox image is not positioned over the original one, so I can't click the checkbox to select it...

Issue originally reported from #1791126: "Select all items on this page" checkbox not working on Kickstart V2