adamlaki

a[target="_blank"]:not([href*="pineco.de"])::after {
    /* You can style it anyway you want... */
    content: '';
    display: inline-block;
    background: transparent url(external-arrow.svg) no-repeat center center;
    background-size: cover;
    width: 1rem;
    height: 1rem;
    margin-left: 0.3rem;
}