.nuvem-escura{
position: relative;
width: 150vw;
height: 100vh;
transform: translateX(-50%);
border-radius: 50%;
background-color: #111;
opacity: 0.5;
animation: desvanecer 10s linear infinite;
}
.luz-brilhante{
position: absolute;
width: 150vw;
height: 50vh;
transform: translateX(-50%);
border-radius: 50%;
background-color: #fff;
opacity: 0;
animation: brilhar 5s linear infinite;
}