#back-to-top {
    position: fixed;
    bottom: 40px;
    right: 30px;
    width: 50px;
    height: 50px;
    background-color: #c00;
    background-image: url("data:image/svg+xml;utf8,<svg fill='white' xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'><path d='M12 2L5 9h5v9h4V9h5z'/></svg>");
    background-repeat: no-repeat;
    background-position: center;
    background-size: 24px 24px;
    border: none;
    border-radius: 50%;
    box-shadow: 0 4px 6px rgba(0,0,0,0.2);
    cursor: pointer;
    display: none;
    z-index: 9999;
    transition: opacity 0.3s ease, transform 0.3s ease;
    color: transparent;
    font-size: 0; /* hide fallback text */
}

#back-to-top:hover {
    background-color: #900;
    transform: scale(1.1);
}