function vertical_align(container, text) {
	container_height = document.getElementById(container).offsetHeight;
	text_height = document.getElementById(text).offsetHeight;
	offset = (container_height - text_height)/2;
	document.getElementById(container).style.paddingTop = offset + "px";
	document.getElementById(container).style.height = container_height - offset;
}

function mailing_list_signup() {
	new_content = document.getElementById("mailing_list_signup_textbox").value;
	if (new_content == "Enter email address to receive updates.") {
		// do nothing
	} else if (new_content == "") {
		// do nothing
	} else {
		var xmlHttp;
		try {
 			// Firefox, Opera 8.0+, Safari
 			xmlHttp=new XMLHttpRequest();
		}
		catch (e) {
  			// Internet Explorer
  			try {
				xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
    			}
  			catch (e) {
    			try {
    				xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
    			}
    			catch (e) {
    				alert("Your browser does not support AJAX!");
    				return false;
    			}
  			}
		}
		xmlHttp.onreadystatechange=function() {
			if(xmlHttp.readyState < 4) {
				document.getElementById("mailing_list_signup_textbox").value='Signing up...';
			} else if(xmlHttp.readyState==4) {	
				var xmlDoc = xmlHttp.responseXML;
				var a = xmlDoc.getElementsByTagName("alert");
				switch(a[0].childNodes[0].nodeValue) {
					case "1": 
						document.getElementById("mailing_list_signup_textbox").value='Thanks for signing up!';
						break;
					case "2":
						alert('There was an error signing up.');
						break;
					case "3":
						document.getElementById("mailing_list_signup_textbox").value='You\'ve already signed up.';
						break;
				}	
    		}
   		}
		var url = "traffic.php";
		url = url + "?from=mailing_list_signup&email=" + new_content;
  		xmlHttp.open("GET",url,true);
  		xmlHttp.send(null);
	}
}