.scroll-top {
        position: fixed;
        bottom: 20px;
        right: 20px;
        width: 45px;
        height: 45px;
        border-radius: 50%;
        border: none;
        background: #0d6efd;
        color: #fff;
        font-size: 20px;
        cursor: pointer;

        /* hidden by default */
        opacity: 0;
        visibility: hidden;
        transform: translateY(20px);
        transition: all 0.3s ease;
    }

    /* class show */
    .scroll-top.show {
        opacity: 1;
        visibility: visible;
        transform: translateY(0);
    }