scroll

//fix menu
	$(window).scroll(function(){
		var js_scroll = $(window).scrollTop();
		var SCROLL_MIN = 820;
		var SCROLL_MAX = 5480;
		if ( js_scroll > SCROLL_MIN ) { 
			$(".js-top-nav").addClass('fixed'); 
			if(js_scroll > SCROLL_MAX) {
				$(".js-top-nav").removeClass('fixed'); 
			};
		}
		else { 
			$(".js-top-nav").removeClass('fixed'); 
		};
	});
//scroll to
	$(".navbar a, .js-btn-top").click(function (){
		var page = $(this).attr("href");

		$('html, body').animate({
			scrollTop: $(page).offset().top + 20
		}, 600);
		return false;
	});


// highlight active link when scrolling
$(function(){
    var sections = {},
        _height  = $(window).height(),
        i        = 0;
    
    // Grab positions of our sections 
    $('.section').each(function(){
        sections[this.name] = $(this).offset().top;
    });

    $(document).scroll(function(){
        var $this = $(this),
            pos   = $this.scrollTop();
            
        for(i in sections){
            if(sections[i] > pos && sections[i] < pos + _height){
                $('a').removeClass('active');
                $('#nav_' + i).addClass('active');
            }  
        }
    });
});

//yet another scrolling with hightlight effect (works for me)
//each marker link would be with section class
//.page is class of page without top menu )
// Navigation
    $('.js-nav a').on('click',function (e) {
        e.preventDefault();

        var target = this.hash,
            $target = $(target);

        $('html, body').stop().animate({
            'scrollTop': $target.offset().top - 20
        }, 500, 'swing', function () {
            // window.location.hash = target;
        });
    });

    function navScroll(){
        $('.section').each(function(){
            var pos = $(this).offset().top;
            var id = $(this).attr('id');
            var top = ($('.page').offset().top - 80);
            if( $(window).scrollTop() >= (pos - 79)){
                $('.js-nav li').removeClass('is-active');
                $('[href = #'+id+']').parent().addClass('is-active');
            }
            if($(window).scrollTop() < top){
                $('.js-nav li').removeClass('is-active');
            }
        });
    }

    $(window).scroll(function() {
        navScroll();
    });
    
    
    ////////==================================================
    //another working method for sticky nav, scroll and hightligt links where scrolling
    //.target - class where to scrolling
    //=========================================================
    
    
    
    
    
    $('a[href^="#"]').on('click',function (e) {
        e.preventDefault();
        var target = this.hash, $target = $(target);
        var offset = ($(window).scrollTop() <= 0) ? 120 : 40;
        $('html, body').stop().animate({
            'scrollTop': ($target.offset().top - offset)
        }, 900, 'swing', function () {
            window.location.hash = target;
        });
    });

    var $anchors = $('.anchor');
    var $nav = $('.top-nav');
    var sticky = function() {
        var scrollTop = $(window).scrollTop();

        if (scrollTop > 0) {
            $nav.addClass('stick');
        } else {
            $nav.removeClass('stick');
        }
        $nav.find('a').removeClass('active');
//Highlight the navigation item
        var $nearest = null;
        $anchors.each(function(index, item){
            var $item = $(item);
            var id = $item.prop('id');
            if (($item.offset().top - 40) <= scrollTop) {
                $nearest = $nav.find('a[href^="#'+ id +'"]');
            }
        });
        if ($nearest !== null) {
            $nearest.addClass('active');
        }
    }
    $(window).scroll(sticky);