stars.css

/* Stars 
------------------------------------- */

#space,
.stars {
    overflow: hidden;
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
}

.stars {
    background-image: radial-gradient(2px 2px at 20px 30px,
            #eee,
            rgba(0, 0, 0, 0)),
        radial-gradient(2px 2px at 40px 70px, #fff, rgba(0, 0, 0, 0)),
        radial-gradient(2px 2px at 50px 160px, #ddd, rgba(0, 0, 0, 0)),
        radial-gradient(2px 2px at 90px 40px, #fff, rgba(0, 0, 0, 0)),
        radial-gradient(2px 2px at 130px 80px, #fff, rgba(0, 0, 0, 0)),
        radial-gradient(2px 2px at 160px 120px, #ddd, rgba(0, 0, 0, 0));
    background-repeat: repeat;
    background-size: 200px 200px;
    animation: zoom 5s infinite;
    opacity: 0;
}

.stars:nth-child(1) {
    background-position: 50% 50%;
    animation-delay: 0s;
}

.stars:nth-child(2) {
    background-position: 20% 60%;
    animation-delay: 1s;
}

.stars:nth-child(3) {
    background-position: -20% -30%;
    animation-delay: 2s;
}

.stars:nth-child(4) {
    background-position: 40% -80%;
    animation-delay: 3s;
}

.stars:nth-child(5) {
    background-position: -20% 30%;
    animation-delay: 4s;
}

@keyframes zoom {
    0% {
        opacity: 0;
        transform: scale(0.5);
        animation-timing-function: ease-in;
    }

    85% {
        opacity: 1;
        transform: scale(2.8);
        animation-timing-function: linear;
    }

    100% {
        opacity: 0;
        transform: scale(3.5);
    }
}