// When the page loads, this function is called.
Event.observe(window, 'load', function() {  
  Event.observe('email', 'click', clearField);
  Event.observe('name', 'click', clearField);
  Event.observe('phone', 'click', clearField);
  Event.observe('details', 'click', clearField);
  Event.observe('quiz', 'click', clearField);
});

function clearField(event) {
	var elem = Event.element(event);
	elem.value = '';
}