https://capella-spb.ru/assets/templates/capella/overhid.js

1var sсTop = window.pageYOffset;
2$(document).ready(function() {
3  var $docEl = $('html, body'),
4    $wrap = $('.navbar'),
5    scrollTop;
6
7  $('#navbar').on('shown.bs.collapse', function(){	
8    overlayOpen();
9   });
10
11  $('#navbar').on('hidden.bs.collapse', function(){
12    overlayClose();
13  });
14  
15  var overlayClose = function() {
16    $.unlockBody();
17    $('body').removeClass('overlay-open');
18  }
19  
20//  function overlayClose() {
21//	$.unlockBody();
22//    $('body').removeClass('overlay-open');
23//  };
24  
25  var overlayOpen = function() {
26    $('body').addClass('overlay-open');
27    $.lockBody();
28  }
29
30  $.lockBody = function() {
31    if(window.pageYOffset) {
32      scrollTop = window.pageYOffset;
33      
34      $wrap.css({
35        top: - (scrollTop)
36      });
37    }
38
39    $docEl.css({
40      height: "100%",
41      overflow: "hidden"
42    });
43  }
44
45  $.unlockBody = function() {
46    $docEl.css({
47      height: "",
48      overflow: ""
49    });
50
51    $wrap.css({
52      top: ''
53    });
54
55    window.scrollTo(0, scrollTop);
56    window.setTimeout(function () {
57      scrollTop = null;
58    }, 0);
59
60  }
61});
62$(document).mouseup(function (e) {
63	//var sсTop = window.pageYOffset;
64	//alert(sсTop);
65    var $target = $(e.target);
66    if ($target.closest('.navbar-collapse').length == 0 && $target.closest('.navbar-toggle').length == 0){
67        $('.navbar-collapse').removeClass('in');
68		$('body').removeClass('overlay-open');
69		$('html, body').css({
70      height: "",
71      overflow: ""
72    });
73//		window.scrollTo(0, sсTop);
74//    	window.setTimeout(function () {
75//    	scTop = null;
76//    	}, 0);
77//		$('.navbar').css({top:''});
78    }
79});