scrolling position fixed code example

Example 1: center position fixed

.centered {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

Example 2: scroll position

$(window).scroll(function() {
	var $height = $(window).scrollTop();
  if($height > 50) {
		//do something
	} else {
		//do something
	}
});