#button-up{
    width: 60px;
    height: 60px;
    background: var(--first-color);
    display: flex;
    justify-content: center;
    align-items: center;
    color: white;
    border-radius: 50%;
    font-size: 20px;
    position: fixed;
    bottom: 50px;
    right: 50px;
    cursor: pointer;
    border: 4px solid transparent;
    transition: all 300ms ease;
    transform: scale(0);
    z-index: 999;
}

#button-up:hover{
    transform: scale(1.1);
    border-color: rgba(0,0,0,0.1);
}