input[type="submit"] {
    font-size: 1rem;
    background: linear-gradient(90deg, #15dd0f, #ee33ff);
    background-size: 200% auto;
    color: transparent;
    -webkit-background-clip: text;
    animation: wave 4s linear infinite;
}

@keyframes wave {
    0% {
        background-position: 0% center;
    }
    100% {
        background-position: 200% center;
    }
}