reset scroll position

app.js

document.addEventListener('template-bound', function() {
  
  var headerPanel = document.querySelector('[main]');
  var pages = document.querySelector('core-pages');

  pages.addEventListener('core-select', function(e) {

    // Only handle the event once
    if (e.detail && e.detail.isSelected) {
      headerPanel.scroller.scrollTop = 0;
    }

  });

});