Folyékony átalakulás

.we-btn-morph {
    position: relative;

    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 18px;

    min-width: 170px;
    height: 54px;

    padding: 0 24px;

    border: 1px solid rgba(142,232,212,.35);
    border-radius: 27px;

    background: #0d1518;
    color: #f2f4f0;

    font-family: Arial, sans-serif;
    font-size: 14px;
    font-weight: 500;
    letter-spacing: .5px;

    cursor: pointer;

    overflow: hidden;

    transition:
        width .55s cubic-bezier(.22,1,.36,1),
        padding .55s cubic-bezier(.22,1,.36,1),
        border-radius .55s cubic-bezier(.22,1,.36,1),
        border-color .4s ease,
        transform .4s cubic-bezier(.22,1,.36,1),
        box-shadow .5s ease;
}

.we-btn-morph::before {
    content: "";

    position: absolute;

    left: -10%;
    top: 50%;

    width: 120%;
    height: 0;

    background: #8ee8d4;

    border-radius: 50%;

    transform:
        translateY(-50%)
        scaleY(0);

    transition:
        transform .6s cubic-bezier(.22,1,.36,1);
}

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

    transition:
        transform .5s cubic-bezier(.22,1,.36,1),
        color .35s ease;
}

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

.we-btn-morph:hover {
    padding-left: 30px;
    padding-right: 30px;

    border-radius: 16px;

    border-color: #8ee8d4;

    transform:
        translateY(-3px);

    box-shadow:
        0 18px 35px rgba(0,0,0,.35);
}

.we-btn-morph:hover::before {
    transform:
        translateY(-50%)
        scaleY(1);
}

.we-btn-morph:hover .we-btn-text {
    color: #081012;

    transform:
        translateX(-3px);
}

.we-btn-morph:hover .we-btn-arrow {
    color: #081012;

    transform:
        translateX(5px)
        scale(1.15);
}

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

Ehhez az animációhoz nincs külön JavaScript.