Blue did not turn out as expected

Got two of these in blue for my daughter's medium brown hair. We were only going to dye the underside for a peekaboo effect. I wanted to get the blue as bold as we could, so I bleached her hair first. I used some extra, just to make sure her hair was completely saturated, and even left it on a little longer than we were supposed to. Her hair turned out a very pale greenish blue that completely disappeared within a couple of weeks. I don't know what we did wrong! We may try again at some point, hoping with a different color we may have better results!

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