#scroll-to-top {
    position: fixed;
    bottom: 40px;
    color: #fff;
    text-align: center;
    line-height: 50px;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    cursor: pointer;
    z-index: 9999;
    font-size: 24px;
    display: none;
    transition: all 0.3s;
}

#scroll-to-top:hover {
    opacity: 0.8;
}

.scroll-to-top-small {
    width: 40px;
    height: 40px;
    line-height: 40px;
    font-size: 18px;
}

.scroll-to-top-medium {
    width: 50px;
    height: 50px;
    line-height: 50px;
    font-size: 24px;
}

.scroll-to-top-large {
    width: 60px;
    height: 60px;
    line-height: 60px;
    font-size: 30px;
}

.scroll-to-top-left {
    left: 40px;
    right: auto;
}

.scroll-to-top-center {
    left: 50%;
    transform: translateX(-50%);
    right: auto;
}

.scroll-to-top-right {
    right: 40px;
    left: auto;
}