@include keyframes(pulse) {
    0% {
        @include box-shadow(0 0 0 0 var(--red-alpha4));
    }
    70% {
        @include box-shadow(0 0 0 10px transparent);
    }
    100% {
        @include box-shadow(0 0 0 0 transparent);
    }
}

.pulse {
    @include animation (pulse 1s ease infinite);
}