var ini_start = -700;
var final_end = 15;
var t;

function move_in()
{	
	var el = document.getElementById('my_slider');
	ini_start = ini_start + 15;
	if (ini_start >= 15)
	{
		stop_count();
	}
	else
	{
		el.style.top = (ini_start) + 'px';
		t = setTimeout("move_in()",1);	
	}
	
}

function move_out()
{
	var el = document.getElementById('my_slider');
	final_end = final_end - 30;
	if (final_end <= -1000)
	{
		stop_count();
	}
	else
	{
		el.style.top = (final_end) + 'px';
		t = setTimeout("move_out()",1);	
	}

}

function stop_count()
{
	clearTimeout(t);
	ini_start = -700;
	final_end = 15;
}

function slider_left()
{
	var el = document.getElementById('my_slider');
	my_width = 500;
	scr_width = screen.width;	
	my_left = (scr_width/2) - (my_width/2);
	el.style.left = (my_left) + 'px';
}