select2/docs/_sass/_anchorjs.scss

// AnchorJS Styles
//
// Styles for AnchorJS elements following the Bootstrap docs styles.
//
// @see https://github.com/twbs/bootstrap/blob/master/docs/assets/css/src/docs.css#L1599

.anchorjs-link {
  float: left;
  width: 1em;
  height: 1em;
  margin-left: -1.2em;
  opacity: 0;
  color: inherit;
  text-align: center;

  &:link,
  &:visited {
    text-decoration: none;
    color: inherit;
  }

  @media (max-width: 480px) {
    display: none;
  }
}

*:hover > .anchorjs-link {
  opacity: .5;
  -webkit-transition: all .16s linear;
       -o-transition: all .16s linear;
          transition: all .16s linear;
}

*:hover > .anchorjs-link:hover,
.anchorjs-link:focus {
  opacity: 1;
}

.anchorjs-icon {
  font-size: 60%;
  vertical-align: .2em;
}