function $(id){
    return document.getElementById(id);
}

function $$(searchClass,node,tag) {
    var classElements = new Array();
    if ( node == null )
	    node = document;
    if ( tag == null )
	    tag = '*';
    var els = node.getElementsByTagName(tag);
    var elsLen = els.length;
    var pattern = new RegExp('(^|\\\\s)'+searchClass+'(\\\\s|$)');
    for (i = 0, j = 0; i < elsLen; i++) {
	    if ( pattern.test(els[i].className) ) {
		    classElements[j] = els[i];
		    j++;
	    }
    }
    return classElements;
}

function addEvent( obj, type, fn ) {
    if (obj.addEventListener) {
	    obj.addEventListener( type, fn, false );
    }
    else if (obj.attachEvent) {
	    obj["e"+type+fn] = fn;
	    obj[type+fn] = function() { obj["e"+type+fn]( window.event ); }
	    obj.attachEvent( "on"+type, obj[type+fn] );
    }
    else {
	    obj["on"+type] = obj["e"+type+fn];
    }
}


var content = $$('tab_content');
var tabs = (function(){
    var els = $('nav').childNodes, children = [];
    for (var i = 0; i < els.length; i++) {
        if (els[i].nodeName.toLowerCase() == 'li') {
            children.push(els[i]);
        }
    }
    return children;
})();
for (var i = 1; i < content.length; i++) {
    content[i].style.display = 'none';
}
addEvent($('nav'), 'click', function(event){
    var target = event.target || event.srcElement;
    if (target.tagName.toLowerCase() == 'a') {
        if (event.preventDefault) { event.preventDefault(); }
        else { event.returnValue = false; }
        target.blur();
        showTab(target.href.substring(target.href.indexOf('#') + 1), target);
    }
});

function showTab(id,tab){
    for (var i = 0; i < content.length; i++) {
        content[i].style.display = 'none';
        tabs[i].className = '';
    }
    tab.parentNode.className = 'selected';
    $(id).style.display = 'block';
}