Zöld hullám

.we-btn-wave {
    position: relative;

    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 16px;

    min-width: 180px;
    height: 54px;

    padding: 0 26px;

    border: 1px solid rgba(63,159,99,.35);
    border-radius: 12px;

    background: #101713;
    color: #f1f3ee;

    font-family: Arial, sans-serif;
    font-size: 14px;
    font-weight: 500;
    letter-spacing: .4px;

    cursor: pointer;
    overflow: hidden;

    transition:
        transform .7s cubic-bezier(.22,1,.36,1),
        border-radius .7s ease,
        box-shadow .7s ease;
}

.we-btn-wave-shape {
    position: absolute;

    left: -25%;
    top: -55%;

    width: 75%;
    height: 210%;

    background: #3f9f63;

    border-radius: 50%;

    transform:
        rotate(-8deg)
        translateX(-35%);

    transition:
        transform 1.15s cubic-bezier(.22,1,.36,1),
        width 1.15s cubic-bezier(.22,1,.36,1),
        border-radius 1.15s ease;
}

.we-btn-wave-text,
.we-btn-wave-arrow {
    position: relative;
    z-index: 2;

    transition:
        transform .9s cubic-bezier(.22,1,.36,1),
        color .65s ease;
}

.we-btn-wave-arrow {
    font-size: 20px;
    line-height: 1;
}

.we-btn-wave:hover {
    transform:
        translateY(-4px);

    border-radius: 18px;

    box-shadow:
        0 20px 42px rgba(0,0,0,.42);
}

.we-btn-wave:hover .we-btn-wave-shape {
    width: 150%;

    transform:
        rotate(-8deg)
        translateX(45%);

    border-radius: 42%;
}

.we-btn-wave:hover .we-btn-wave-text {
    color: #08110b;

    transform:
        translateX(-4px);
}

.we-btn-wave:hover .we-btn-wave-arrow {
    color: #08110b;

    transform:
        translateX(8px)
        scale(1.12);
}

.we-btn-wave:active {
    transform:
        translateY(-1px)
        scale(.97);
}

Ehhez az animációhoz nincs külön JavaScript.