I'm using the following to animate the screen;

function goToByScroll(id){
  $('html,body').animate({scrollTop: $("#"+id).offset().top},'slow');
which works great on desktop browers, but on safari mobile, the menu/nav doesn't work correctly.

The nav is inside a fixed div. When you click a button the first time it scrolls to the area fine. But after that none of the buttons work. If you move the screen slightly by finger scolling the buttons work again one more time.

A link to the example of the work in progress is here

Any help on this would be greatly received.