1html {
2  scroll-behavior: smooth;
3}
4
5/* No support in IE, or Safari
6You can use this JS polyfill for those */
7http://iamdustan.com/smoothscroll/
8

1// handle links with @href started with '#' only
2$(document).on('click', 'a[href^="#"]', function(e) {
3    // target element id
4    var id = $(this).attr('href');
5
6    // target element
7    var $id = $(id);
8    if ($id.length === 0) {
9        return;
10    }
11
12    // prevent standard hash navigation (avoid blinking in IE)
13    e.preventDefault();
14
15    // top position relative to the document
16    var pos = $id.offset().top;
17
18    // animated top scrolling
19    $('body, html').animate({scrollTop: pos});
20});

1// Select all links with hashes
2$('a[href*="#"]')
3  // Remove links that don't actually link to anything
4  .not('[href="#"]')
5  .not('[href="#0"]')
6  .click(function(event) {
7    // On-page links
8    if (
9      location.pathname.replace(/^\//, '') == this.pathname.replace(/^\//, '') 
10      && 
11      location.hostname == this.hostname
12    ) {
13      // Figure out element to scroll to
14      var target = $(this.hash);
15      target = target.length ? target : $('[name=' + this.hash.slice(1) + ']');
16      // Does a scroll target exist?
17      if (target.length) {
18        // Only prevent default if animation is actually gonna happen
19        event.preventDefault();
20        $('html, body').animate({
21          scrollTop: target.offset().top
22        }, 1000, function() {
23          // Callback after animation
24          // Must change focus!
25          var $target = $(target);
26          $target.focus();
27          if ($target.is(":focus")) { // Checking if the target was focused
28            return false;
29          } else {
30            $target.attr('tabindex','-1'); // Adding tabindex for elements not focusable
31            $target.focus(); // Set focus again
32          };
33        });
34      }
35    }
36  });