What happens if you use hair dye that was meant for gray hair?

I'm dying my hair black, and since I was silly, I grabbed any black hair dye off the shelves thinking that black is black. If it were a brunette or red shade, I would've read the labels, other than just looking at the colour. When I got home, I realized I got hair dye that you're supposed to use if you have "50% or more gray hair." My hair is dark brown right now with a few lighter strands because it used to be golden brown. Would it be a bad idea to still use this hair dye?

The dye is "Nice'N Easy Gray Solution."

What happens if you use hair dye that was meant for gray hair?

The colour you chose will be fine .You will just get better coverage. Gray is harder to cover than natural hair so it may be a little darker thats all.