.effect{
    width:100%;
    height:100%;
    padding:10px;
    filter:contrast(10);
}
.big_ball{
    width:100px;
    height:100px;
    background: #000;
    padding:10px;
    border-radius: 50%;
    margin:0 auto;
    z-index:1;
    filter:blur(5px);
}
.small_ball{
    position: absolute;
    width:60px;
    height:60px;
    background: #f00;
    padding:10px;
    border-radius: 50%;
    top:30px;
    z-index:2;
    filter:blur(5px);
    animation:rball 6s infinite;
}
@keyframes rball{
0%{
    margin-right:90%;
    margin-left:10%;
}
50%{
    margin-right:10%;
    margin-left:90%;
}
100%{
    margin-right:90%;
    margin-left:10%;
}
}