.loader {
    border: solid;
    border-color: #f3f3f3;
    border-top: solid;
    border-top-color: #3498db;
    border-radius: 50%;
    border-width: 16px;
    width: 120px;
    height: 120px;
    animation: spin linear infinite;
    animation-duration: 2s;
    display: none;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}