.snowfall-flakes:nth-child(4n)
{
	opacity: .2;	
}

.snowfall-flakes:nth-child(4n+1)
{
	opacity: .4;	
}

.snowfall-flakes:nth-child(4n+2)
{
	opacity: .6;	
}

.snowfall-flakes:nth-child(4n+3)
{
	opacity: .8;	
}