#scrollTopBtn {
        display: none;
        /* hidden by default */
        position: fixed;
        bottom: 30px;
        right: 30px;
        width: 50px;
        height: 50px;
    background-color: rgb(109, 13, 13);
        /* Black → Red */
        color: #fff;
        border: none;
        border-radius: 50%;
        box-shadow: 0 5px 15px rgba(0, 0, 0, 0.3);
        cursor: pointer;
        font-size: 24px;
        text-align: center;
        line-height: 50px;
        z-index: 1000;
        transition: transform 0.3s, opacity 0.3s;
    }

    #scrollTopBtn:hover {
        transform: scale(1.1);
        opacity: 0.9;
    }