function getBrowserCodeName()
{
	var name = null;
	
	if ( document.getElementById && !document.all )
	{
		name = 'NS6';
	}
	else if ( document.all )
	{
		name = 'IE';
	}
	else if ( navigator.appName == 'Netscape' && navigator.appVersion.charAt( 0 ) == '4' )
	{
		name = 'NS';
	}
	else if ( navigator.userAgent.indexOf( 'Mac' ) != -1 )
	{
		name = 'MAC';
	}
	
	return name;
}

function deplDiv(){ 	
	var id = 'scroll_div';
	var obj = document.getElementById( id ).style; 
	var winY = document.documentElement.scrollTop;
	var winH = document.documentElement.clientHeight;
	var obj_top = ( getBrowserCodeName() == 'IE' ) ? obj.pixelTop : parseInt(obj.top);
	var vitesse = 0.2;
	var remonter_de = 200;
	
	var go_y = winY + ( winH / 2 ) - ( parseInt(obj.height) / 2 ) - remonter_de; 
	var distance =  Math.abs( go_y - obj_top );
	var smooth = distance * vitesse;
	if ( go_y < obj_top ) smooth *= -1;
	if ( ( (obj_top + smooth) >= 0 ) && ( winH > parseInt(obj.height) ) ){
		if ( getBrowserCodeName() == 'IE' ){
			obj.pixelTop += smooth;
		}else if ( getBrowserCodeName() == 'NS6' || getBrowserCodeName() == 'NS' ){
			obj.top = (obj_top + smooth) + 'px';
		}
	}
	if ( winY == 0 ){
		if ( getBrowserCodeName() == 'IE' ){
			obj.pixelTop = 0;
		}else if ( getBrowserCodeName() == 'NS6' || getBrowserCodeName() == 'NS' ){
			obj.top = '0px';
		}
	}
	setTimeout("deplDiv()", 20 );
}
deplDiv();