function initFootnotes() {
	var elPreview = document.getElementById('footnote-preview');
	
	function mouseoverFootnote(evt) {
		var fnText = document.querySelector(evt.target.getAttribute('href') + ' p').innerHTML;
		elPreview.innerHTML = fnText;
		elPreview.style.display = 'block';
		elPreview.style.top = (evt.target.getBoundingClientRect().top + 16) + 'px';
		elPreview.style.left = evt.target.getBoundingClientRect().left + 'px';
	}

	function mouseoutFootnote(evt) {
		elPreview.style.display = 'none';
	}

	document.querySelectorAll('a.footnote-reference').forEach(function(el) {
		el.addEventListener('mouseenter', mouseoverFootnote);
		el.addEventListener('mouseleave', mouseoutFootnote);
	});
}

if (document.readyState === 'complete' || document.readyState === 'interactive') {
	initFootnotes();
} else {
	document.addEventListener('DOMContentLoaded', initFootnotes);
}