window.onload = init

function init()
{
	document.getElementById("extra-content").style.display = "none"
	var Sub = document.getElementById("substance");
	Sub.getElementsByTagName("a")[1].onclick = change
	
}

function change()
{
	document.getElementById("extra-content").style.display = "block"
	var Sub = document.getElementById("substance");
	Sub.getElementsByTagName("a")[1].style.display = "none"
	Sub.getElementsByTagName("a")[2].onclick = revert
}

function revert()
{
	document.getElementById("extra-content").style.display = "none"
	var Sub = document.getElementById("substance");
	Sub.getElementsByTagName("a")[1].style.display = "block"
	Sub.getElementsByTagName("a")[1].onclick = change
}