.button-up {
    line-height: 0;
    position: fixed;
    bottom: 40px;
    width: 42px;
    height: 42px;
    cursor: pointer;
    transition: opacity 0.2s, fill 0.2s;
    pointer-events: none;
    opacity: 0;
    fill: #000;
}

.button-up.is-show {
    z-index: 9999;
    pointer-events: all;
    opacity: 1;
}

.button-up:hover {
    opacity: 0.7;
}

.button-up svg {
    width: 100%;
    height: 100%;
}