function randomFromTo(from, to){
	return Math.floor(Math.random() * (to - from + 1) + from);
}

function moveRandom() {
	var id = 'box';
	/* get container position and size
	* -- access method : cPos.top and cPos.left */
	var cPos = $('#container').offset();
	var cHeight = $('#container').height();
	var cWidth = $('#container').width();

	// get box padding (assume all padding have same value)
	var pad = parseInt($('#container').css('padding-top').replace('px', ''));

	// get movable box size
	var bHeight = $('#'+id).height();
	var bWidth = $('#'+id).width();

	// set maximum position
	maxY = cPos.top + cHeight - bHeight - pad - 100;
	maxX = cPos.left + cWidth - bWidth - pad -80;

	// set minimum position
	minY = cPos.top + pad;
	minX = cPos.left + pad;

	// set new position
	newY = randomFromTo(minY, maxY);
	newX = randomFromTo(minX, maxX);

	$('#box').animate({
		top: newY,
		left: newX
	}, 3500, function() {
	});

}