var windw = this;
var wrapper = document.getElementById('main');
var sticky = document.getElementById('main');

$.fn.followTo = function ( ) {
    var $this = this,
        $window = $(windw);

    var pos = wrapper.scrollHeight;    
    
    $window.scroll(function(e){
        if ($window.scrollTop() >= wrapper.scrollHeight - 130) {
            $this.css({
                position: 'absolute',
                top: pos
            });
        } else {
            $this.css({
                position: 'fixed',
                top: ''
            });
        }
    });
};

$('#main-arrow').followTo();