﻿// Modal views
$(function (app) {
    var modals = {
        $el: $('#modal-root'),
        show: function (modal) {
            // hide collapse
            $('.nav-collapse').collapse('hide');
            // render modal
            var el = modal.render().el;
            this.$el.html(el);
            modal.$el.modal('show');
        }
    };
    app.Modals = modals;
}(window.App));

﻿// Modal views
$(function (app) {
    var modals = {
        $el: $('#modal-root'),
        show: function (modal) {
            var el = modal.render().el;
            this.$el.html(el);
            modal.$el.modal('show');
        }
    };
    app.Modals = modals;
}(window.App));

--- 
+++ 
@@ -3,6 +3,9 @@
     var modals = {
         $el: $('#modal-root'),
         show: function (modal) {
+            // hide collapse
+            $('.nav-collapse').collapse('hide');
+            // render modal
             var el = modal.render().el;
             this.$el.html(el);
             modal.$el.modal('show');
Hide collapse before showing a modal

This will hopefully work out great on a mobile device.
