.operation-unit() {
  color: var(--link-6);
  text-decoration: none;
  outline: none;
  cursor: pointer;
  transition: color 0.3s;

  &:focus,
  &:hover {
    color: var(--link-onHover-color);
  }

  &:active {
    color: var(--link-onActive-color);
  }
}