body {
    width: 100%;
    height: 100vh;
    background-size: 700% 700%;
    background-image: repeating-linear-gradient(
		-45deg,
		var(--farbeblau) 0%,  /* blau */
		var(--farbegruen) 15%, /* grün */
		var(--farberosa) 30%,
		var(--farbeblau) 45%  /* blau */
	);
    animation: diagonal alternate 30s infinite;
}
@keyframes diagonal {
    0% {background-position: 0% 50%}
    100% {background-position: 100% 50%}
}