function kesu(ev) {
	var element = (ev.target||ev.srcElement);
	element.style.backgroundColor = "white";
}

function addAll() {
	var i, item;
	var checks = document.getElementsByTagName("span");
	for (i=0; i<checks.length; i++) {
		item = checks[i];
		if (item.getAttribute("class") == "kesu") {
			item.addEventListener("click", kesu, false);
		}
	}
}
window.onload = addAll;