.spinner { 
        border: 4px solid #f3f3f3; 
        border-top: 4px solid #007cba; 
        border-radius: 50%; 
        width: 40px; 
        height: 40px; 
        animation: spin 1s linear infinite; 
        margin: 0 auto; 
    }
    @keyframes spin { 
        0% { transform: rotate(0deg); } 
        100% { transform: rotate(360deg); } 
    }