Szövegcsere

.we-btn-swap {
    position: relative;

    display: inline-flex;
    align-items: center;
    justify-content: center;

    width: 180px;
    height: 54px;

    padding: 0;

    border: 1px solid rgba(255,255,255,.15);
    border-radius: 27px;

    background: #10191c;
    color: #f2f4f0;

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

    cursor: pointer;
    overflow: hidden;

    transition:
        transform .45s cubic-bezier(.22,1,.36,1),
        border-radius .45s ease,
        border-color .4s ease,
        box-shadow .45s ease;
}

.we-btn-swap-label {
    position: relative;

    display: block;

    width: 100%;
    height: 20px;

    overflow: hidden;
}

.we-btn-swap-front,
.we-btn-swap-back {
    position: absolute;

    left: 0;
    width: 100%;

    display: flex;
    align-items: center;
    justify-content: center;

    transition:
        transform .55s cubic-bezier(.22,1,.36,1),
        opacity .4s ease;
}

.we-btn-swap-front {
    top: 0;
    transform: translateY(0);
}

.we-btn-swap-back {
    top: 0;
    transform: translateY(100%);
    opacity: 0;
}

.we-btn-swap:hover {
    transform:
        translateY(-3px);

    border-radius: 15px;
    border-color: rgba(142,232,212,.55);

    box-shadow:
        0 18px 38px rgba(0,0,0,.4);
}

.we-btn-swap:hover .we-btn-swap-front {
    transform: translateY(-100%);
    opacity: 0;
}

.we-btn-swap:hover .we-btn-swap-back {
    transform: translateY(0);
    opacity: 1;
}

.we-btn-swap:active {
    transform:
        translateY(0)
        scale(.97);
}

Ehhez az animációhoz nincs külön JavaScript.