.nav__indicator {
  position: absolute;
  top: anchor(center);
  left: anchor(center);
  width: calc(anchor-size(width) - 8px);
  height: calc(anchor-size(height) - 8px);
  position-anchor: --active;
  translate: -50% -50%;
  background: white;
  mix-blend-mode: difference;
}
nav ul {
  scroll-target-group: auto;
}
nav ul a:target-current {
  anchor-name: --active;
}