.content {
    height: 2000px; 
    padding: 20px;
}
#scrollToTopBtn {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background-color: #555;
    color: #fff;
    border: none;
    padding: 15px;
    border-radius: 50%;
    cursor: pointer;
    display: none; 
    z-index: 1000; 
    transition: background-color 0.3s;
}
#scrollToTopBtn {
    width: 48px;
    height: 48px;
    padding: 13px !important;
}
#scrollToTopBtn.highlight {
    background-color: #333; 
}
#scrollToTopBtn:hover {
    background-color: #666;
}
.arrow-up-icon {
    font-size: 20px;
    display: inline-block;
}