.spinner {
    border: 4px solid #f3f3f3;
    border-top: 4px solid #3498db;
    border-radius: 50%;
    width: 100px;
    height: 100px;
    animation: girar 4s linear infinite;
    position: absolute;
    top: 400px;
    left: 900px;
}

.oculto {
    display: none;
}

@keyframes girar {
    0% {
        transform: rotate(0deg);
    }

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