var c = 0;

function collapse(divId) {
	
	var id = divId;
	
	t=setTimeout(function(){collapse(id)}, 10);
	//Speeds up collapse as time passes
	c = c+1;
	
	var divElement = document.getElementById(id);
	if(isNaN(parseInt(divElement.style.height))) {
		//If height is not set in css, get height from element
		var divHeight = parseInt(divElement.offsetHeight);
	} else {
		var divHeight = parseInt(divElement.style.height);
	}
	
	//Reduce height by c
	divElement.style.height = (divHeight-c)+'px';
	
	//When height cannot get any smaller
	if (parseInt(divElement.style.height) < 1) {
		clearTimeout(t);
		c = 0;
		divElement.style.display = 'none';
	}
	
}