button {
    position: relative;
    overflow: hidden;
    transition: background 400ms;
}

button .ripple {
    border-radius: 50%;
    background-color: rgba(255, 255, 255, 0.7);
    position: absolute;
    transform: scale(0);
    animation: ripple 0.6s linear;
}

@keyframes ripple {
    to {
        transform: scale(2.5);
        opacity: 0;
    }
}