Use this code for smoth scroll

smooth_scroll.js

// jQuery smooth scroll
$('li.smooth-scroll a').bind('click', function(event){
    event.preventDefault();
    
    var $anchor = $(this);
    var headerH = '40';
    $('html, body').stop().animate({
        scrollTop : $($anchor.attr('href')).offset().top - headerH + "px"
    }, 1200, 'linear');
}); 


// Bootstrap scroll psy
$('body').scrollspy({ 
    target: '.navbar-collapse',
    offset: 95
});