sass-site/source/assets/css/components/_link-header.scss

h1, h2, h3, h4, h5, h6 {
  a.anchor {
    display: block;
    float: left;
    vertical-align: middle;
    margin: {
      left: -1.5rem;
      top: -3px;
    }
    width: 1.5rem;
    background: none;
    border: 0;

    &::after {
      visibility: hidden;
      font: {
        size: 1rem;
        weight: normal;
      }
      content: "\1F517";
    }
  }

  &:hover a.anchor::after {
    visibility: visible;
  }

  &:target {
    animation-name: highlight-header;
    animation-duration: 5s;
  }
}

@keyframes highlight-header {
  from {
    background-color: $sl-color--dawn-pink;
  }

  to {
    background-color: unset;
  }
}