How do I get a thin border in qtip with round corners?

Question

I try to get a thin border with round corners for the tip in qtip, using:

border: {width: 1, radius: 7, color: "#B8E25E"}

(Like explained here: http://craigsworks.com/projects/qtip/docs/tutorials#borders)

But the border is then getting quite thick, like 7 or something, is there a way to get a thin border with round corners?