function changePrevious(elem,newClass) {
	prevElem = elem.previousSibling;
	while(prevElem.innerHTML == null) {
		prevElem = prevElem.nextSibling;
	}
	prevElem.className = newClass;
}
function changeNext(elem,newClass) {
	nextElem = elem.nextSibling;
	while(nextElem.innerHTML == null) {
		nextElem = nextElem.nextSibling;
	}
	nextElem.className = newClass;
}