.to-top-btn {
    position: fixed;
    bottom: 90px;
    right: 20px;           
    background: #0d6efd;    
    color: #fff;
    border: none;
    width: 40px;            
    height: 40px;
    border-radius: 50%;    
    font-size: 18px;
    display: none;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    z-index: 999;
    padding: 0;              /* remove padding to keep it circle */
}