.rain-wash {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 200%;
    background: linear-gradient(to bottom,
            transparent 0%,
            rgba(0, 255, 255, 0.15) 50%,
            transparent 100%);
    animation: rainWashMove 5s ease-in-out infinite;
    pointer-events: none;
    z-index: -1;
}

@keyframes rainWashMove {
    0% {
        transform: translateY(-100%);
    }

    100% {
        transform: translateY(100%);
    }
}