title: Smooth scroll with external link
body: <p>I have a simple menu with 3 anchor and 1 external link.
  I am using this for smooth scrolling:</p>
  
  <pre><code>        $('.header-menu a').on('click', function (e) {
              e.preventDefault();
  
              var target = this.hash,
                  $target = $(target);
  
              $('html, body').stop().animate({
                  'scrollTop': $target.offset().top - 55
              }, 700, 'swing');
          });
  </code></pre>
  
  <p>which works great with anchor links but it doesnt work on external link in the menu.
  When i remove e.preventDefault();, then it works, but there is weird page flicker when i click on the links.</p>
  
  <p>What is the solution to enable external links?
  Thanks!</p>