// CSS dropdown menus

var arrDropdowns = new Array("about", "series", "topics", "periods");

function setDropdowns(str) {
	for(i=0; i<arrDropdowns.length; i++) {
		document.getElementById(arrDropdowns[i] + "Dropdown").style.top = "210px";
		document.getElementById(arrDropdowns[i] + "Dropdown").style.left = document.getElementById(arrDropdowns[i] + "Link").offsetLeft + document.getElementById("wrapper").offsetLeft + 20 + "px";
	}
	hideDropdowns(str);
}
function hideDropdowns(str) {
	for(i=0; i<arrDropdowns.length; i++) {
		if(str != arrDropdowns[i]) {
			document.getElementById(arrDropdowns[i] + "Dropdown").style.display = "none";	
			document.getElementById(arrDropdowns[i] + "Arrow").src = "images/right_arrow.gif";
		}
	}
}
function showDropdown(str) {
	setDropdowns(str);
	document.getElementById(str + "Dropdown").style.display = "inline";
	document.getElementById(str + "Arrow").src = "images/down_arrow.gif";
}