.hover-bild-container {
    position: relative;
}

.hover-bild-container .hover-bild-normal {
    position: relative;
    z-index: 1;
    margin-bottom: 0;
}

.hover-bild-container .hover-bild-zwei {
    position: absolute;
    z-index: 2;
    top: 0;
    left: 0;
    width: 100%;
    margin-bottom: 0;

    opacity: 0;
    transition: opacity 0.4s ease;
}

.hover-bild-container:hover .hover-bild-zwei {
    opacity: 1;
}