Answer by ibrahimyilmaz for Prevent BODY from scrolling when a modal is opened

This is the best solution for me:

Css:

.modal {
     overflow-y: auto !important;
}

And Js:

modalShown = function () {
    $('body').css('overflow', 'hidden');
},

modalHidden = function () {
    $('body').css('overflow', 'auto');
}