Part 2 - adding the .scroll-block class to the post node for the exiting transition

Post.js

  onExit = () => {
    /* same code */
    this.to = this.getPreviewStyleAndPosition();

    const scrollTop = windowScroll.get('top');
    this.post.classList.add('scroll-block');
    this.postScroll.set('top', scrollTop);
  };