title: scrollIntoView() with fixed header
body: <p>This is probably a simple question but I need some help.</p>
  
  <p>I have this code:</p>
  
  <pre><code>var lastitem='';
  (function($) {
  
  var allPanels = $('.accordion&gt; dd').hide();
  
  $('.accordion &gt; dt &gt; a').click(function() {
      allPanels.slideUp();
      if ($(this).text() != lastitem) {
          $(this).parent().next().slideDown();
          lastitem = $(this).text();
          $(this).get(0).scrollIntoView({
              behavior: "smooth", // or "auto" or "instant"
              block: "start" // or "end"
          });
      } else {
          lastitem = '';
      };
      return false;
    });
  
  })(jQuery);
  </code></pre>
  
  <p>And I have a fixed header, so when I click on the accordion it scrolls into viewport, the problem is my fixed header. I would need to scroll into viewport + 100px from top.</p>
  
  <p>Something like:</p>
  
  <pre><code>$(this).get(0).scrollIntoView({
      behavior: "smooth", // or "auto" or "instant"
      block: "start + 100px" // or "end"
  });
  </code></pre>
  
  <p>That's all, any suggestion? thank you!!</p>