scss-framework/components/_linkfx.scss

.component-linkfx {
  &:before {
    position: absolute;
    content: '';
    bottom: .29rem;
    border-bottom: 1px solid currentColor;
    width: 0;
    height: 1px;
    transition: width .25s;
  }

  &:hover:before {
    width: 100%;
  }
}