#loader {
    border: 4px solid #f3f3f3;
    border-radius: 50%;
    border-top: 4px solid #444444;
    width: 70px;
    height: 70px;
    animation: spin 1s linear infinite;
}

#loader2 {
    border: 2px solid #f3f3f3;
    border-radius: 50%;
    border-top: 2px solid #444444;
    width: 35px;
    height: 35px;
    animation: spin 1s linear infinite;
}

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

.center {
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    margin: auto;
}