Fibonacci spiral

@grid: 1 / 100vw 100vh / #125cde;

background: @doodle2000(
  @content: @svg(
    viewBox: -50 -50 100 100 p -20;
    circle*500 {
      fill: hsl($(120-90*@cos.n), 80%, 50%);
      r: @sqrt(@n/45);
      cx: $(@n*.618^4 * cos(2π*@n*.618));
      cy: $(@n*.618^4 * sin(2π*@n*.618));
    }
  );
) 50% / cover;