Dwitter: Plasma


      for(w=c.width=320,i=2e4;i--;x.fillRect(a,b,2,3))a=2*i%w,b=i/(h=90),x.fillStyle=`hsl(${(C(n=a/h+l)+S((b-a)/h+C(1.7*l))+C(S(n)+3*l))*h} 50%50`


      140 bytes

* uses Dwitter code golf minimal host environment