body{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
.container{
    width: 100vw;
    height: 100vh;
    background: radial-gradient(circle, #333, #111, #000);
    position: relative;
}
.star{
    position: absolute;
    top: 50px;
    left: 20%;
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background-color: #808080;
    -webkit-animation: glow 1s ease-in-out infinite alternate;
    -moz-animation: glow 1s ease-in-out infinite alternate;
    animation: glow 1s ease-in-out infinite alternate;
    transition: 5s;
}

.star:nth-child(even) {
    background: #f9f871;
}

@keyframes glow{
    from{
        box-shadow: 0 0 10px #fff, 0 0 20px #fff, 0 0 30px #ccc, 0 0 40px #666, 0 0 50px #ccc, 0 0  60px #ccc, 0 0 70px #fff;
    }
    to {
    box-shadow: 0 0 20px #fff, 0 0 30px #fff, 0 0 40px #fff, 0 0 50px #ccc, 0 0 60px #ccc, 0 0 70px #ccc, 0 0 80px #fff;
    }
}