#back-to-top {
    position: fixed;
    bottom: 16px;
    right: 8px;
    width: 44px;
    height: 44px;
    background: #ef5f1f;
    color: #fff;
    border: none;
    border-radius: 0px;
    font-size: 20px;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: opacity 0.3s, visibility 0.3s, transform 0.3s;
    z-index: 9999;
    display: flex;
    align-items: center;
    justify-content: center;
}

#back-to-top span {
    display: inline-block;
    transform: rotate(90deg);
    font-size: 22px;
    line-height: 1;
}

#back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

#back-to-top:hover {
    background: #d44e14;
}