function switch_tab(btn, tab)
{
	var btns = btn.parentNode.getElementsByTagName('button');
	for(i = 0; i < btns.length; i++) {
		btns[i].className = '';
	}
	btn.className = 'cur';
	btn.blur();
	for(i = 1; i <= 20; i++) {
		t = document.getElementById('tabcontent' + i);
		if(!t) break;
		t.style.display = i == tab ? '' : 'none';
	}
}

var nds;
var nds_gold;
var towers;
var towers_gold;
var slider;

function start()
{
	nds = {element: document.getElementById('nds'), opacity: 0, increment: 0.02};
	nds_gold = {element: document.getElementById('nds-gold'), opacity: 0, increment: 0.02};
	towers = {element: document.getElementById('logogo'), opacity: 0, increment: 0.02, timer: null};
	towers_gold = {element: document.getElementById('logo-gold'), opacity: 0, increment: 0.02, timer: null};
	slider = {element: document.getElementById('contact'), left: 150, left2: 0, increment: -5, timer: null};
	nds.timer = setInterval('fade_in(nds)', 40);
	setTimeout("towers.timer = setInterval('fade_in(towers)', 40)", 1500);
	setTimeout("slider.timer = setInterval('slide_left(slider)', 10)", 4000);

}

function fade_in(fader)
{
	fader.opacity += fader.increment;
	if(fader.opacity >= 1) {
		fader.opacity = 1;
		clearInterval(fader.timer);
		fader.timer = null;
	}
	fader.element.style.opacity = fader.opacity;
	fader.element.style.filter = 'alpha(opacity=' + fader.opacity * 100 + ')';
}

function fade_out(fader)
{
	fader.opacity -= fader.increment;
	if(fader.opacity <= 0) {
		fader.opacity = 0;
		clearInterval(fader.timer);
		fader.timer = null;
	}
	fader.element.style.opacity = fader.opacity;
	fader.element.style.filter = 'alpha(opacity=' + fader.opacity * 100 + ')';
}

function make_gold(f)
{
	fader = eval(f);
	if(fader.timer) clearInterval(fader.timer);
	fader.timer = setInterval('fade_in(' + f + ')', 20);
}

function make_silver(f)
{
	fader = eval(f);
	if(fader.timer) clearInterval(fader.timer);
	fader.timer = setInterval('fade_out(' + f + ')', 20);
}

function slide_left(slider)
{
	slider.left += slider.increment;
	if(slider.left <= slider.left2) {
		slider.left = slider.left2;
		clearInterval(slider.timer);
	}
	slider.element.style.left = slider.left + 'px';
}