Part 3 - Styling the underlay so it gets a blur

Post.scss

.page-post .underlay {
  position: fixed;
  top: -10vh;
  left: 0;
  z-index: 0;
  width: 100vw;
  height: 120vh;
  background-color: #fff;
  transition: opacity 400ms ease;
  &::before {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    content: '';
  }
}

.page-post.post-dragged .underlay {
  background-color: transparent;

  backdrop-filter: blur(20px);
}