@mixin wave {
    0%,
    100% {
        transform: none;
        transform-origin: center;
    }
    20%,
    60% {
        transform: rotate(-#{$wave});
    }
    40%,
    80% {
        transform: rotate(#{$wave});
    }
}

@keyframes wave-in {
    @include wave;
}

@keyframes wave-out {
    @include wave;
}