Final answer:
The font color used to display 'Hi' is green.
Step-by-step explanation:
The color font used to display 'Hi' is green. The font color is determined by the 'color' property in the CSS rules. In this case, the 'color' property is set to 'green' for the '.fancy' class. Since the 'Hi' text is wrapped in a span with the '.fancy' class, the font color will be green.