wagtail/client/scss/components/_human-readable-date.scss

// Displays 'timesince' formatted date with full date in tooltip
.w-human-readable-date {
  appearance: none;
  background: transparent;
  border: 0;
  padding: 0;
  color: inherit;
  text-align: start;
  line-height: inherit;
  text-decoration: underline;
  text-decoration-style: dotted;
  text-decoration-thickness: 1px;
  text-underline-offset: 1px;
}