old_contents: export class ScrollToTop {
    run(instruction, next) {
      document.body.scrollTop = 0;
      return next();
    }
  }
  
new_contents: export class ScrollToTop {
    run(instruction, next) {
      this.scrollSmooth();
      return next();
    }
  
    scrollSmooth() {
      let element = document.getElementsByTagName('main')[0];
      let movingFrequency = 15;
      let hops = 33;
      let gap = element.scrollTop / hops;
  
      for (var i = 1; i <= hops; i++) {
        (function() {
          setTimeout(() => {
            element.scrollTop = Math.max(element.scrollTop - gap, 0);
          }, movingFrequency * i);
        })();
      }
    }
  }
  
subject: fix scroll to top on routing