@exadel/esl/modules/esl-anchornav/core.css

Exadel Smart Library (ESL) is the lightweight custom elements library that provide a set of super-flexible components

[esl-anchor]:empty {
  margin-block-end: -2px;
  height: 2px;
}
esl-anchornav {
  display: block;
}
[esl-anchornav-sticked] {
  position: sticky;
  top: 0;
}