Some people use "dirty blond" or "sandy blond" way, way further into light brown than I would (which explains a lot about various characters who get described as blond in fanfic and I'm like "that's clearly brown".)

Some people have an in-between for "brown-haired" instead of a blond/brunet dichotomy. That's kind of where I am - I have hair that's somewhere between light and medium brown depending on how much sunlight there is, and I would always just go with "brown-haired" not "brunette", brunette in my head is for people who have those pretty deep browns, not just plain brown.