var acc = document.getElementsByClassName("accordion");
var i;

for (i = 0; i < acc.length; i++) {
  acc[i].onclick = function() {
	this.classList.toggle("active");
	var panel = this.nextElementSibling;
	if (panel.style.maxHeight){
	  panel.style.maxHeight = null;
	} else {
	  panel.style.maxHeight = panel.scrollHeight + "px";
	} 
  }
}