body{
    margin: 0;
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: left;
    background-color: #000;
    overflow: hidden;
}
.contain{
    font-size: 10px;
    width: 40em;
    height: 40em;
    position: relative;
}
.sun{
    position: absolute;
    top:15em;
    left: 15em;
    width: 10em;
    height: 10em;
    /*background-color: #ffff00;*/
    border-radius: 50%;
    box-shadow: 0 0 5em white;
    animation: sunglow 1s infinite alternate
}
/*add on*/
@keyframes sunglow {
    0% { background-color: yellow; }
    100% { background-color: white; }
}
.earth, .moon{
    position: absolute;
    border-style: solid;
    border-color: white transparent transparent transparent;
    border-width: 0.1em 0.1em 0 0;
    border-radius: 50%;
    
}
@keyframes orbit{
    to {
        transform: rotate(360deg);
    }
}
.earth{
    top:5em;
    left: 5em;
    width: 30em;
    height: 30em;
    animation: orbit 36.5s linear infinite;
}
.moon{
    top: 0.5em;
    left: 21.6em;
    width: 8em;
    height: 8em;
    animation: orbit 2.7s linear infinite;
}
.earth::before,
.moon::before{
    content: '';
    position: absolute;
    border-radius: 50%;
}
.earth::before{
    top: 2.8em;
    right: 2.8em;
    width: 3em;
    height: 3em;
    background-color:#00ffff;
}
.moon::before{
    top: 0.8em;
    right: 0.2em;
    width: 1.2em;
    height: 1.2em;
    background-color:silver;
}