.particle{
    position:absolute;
    width:8px;
    height:8px;
    border-radius:50%;
    background:rgba(255,215,0,.5);
    animation:particleFloat linear infinite;
}

@keyframes particleFloat{
    from{
        transform:translateY(0) scale(1);
        opacity:0;
    }
    20%{
        opacity:1;
    }
    to{
        transform:translateY(-250px) scale(.2);
        opacity:0;
    }
}