more consistent hidden fields
ensures that we always use the hidden attribute rather than "display: none" or a mix of both. The reason being is that setting an element to "display: none" will not allow it to be displayed by removing the hidden attribute. we have a css rule that applies "display: none" to elements that have the 'hidden' attribute. JQuery methods hide() and show() add and remove 'display: none' respectively so we need to steer clear of these methods since they will interfere with the behaviour of the 'hidden' attribute and the associated CSS.