yes this is fine. Its also normal. Its also what should happen. Congrats on your first homebrew!!! The separation you are seeing is the yeast falling to the bottom. The yeast work really hard for a few days untill almost all the sugar is consumed, and then they fall to the bottom. Its called flocculation. When the yeast flocculate, they fall out of the beer and end up in the bottom of the fermenter. BUT, this does not mean that all the yeast have fallen. There are still some residual sugars that need to be slowly consumed by the yeast. If you took a gravity measurement now, it would be about 75% less than what it was at the time you pitched the yeast. In about a week, it should be around 80% or above your Original Gravity. (OG) After a cold crash (below 40 degrees or so for a couple days) The rest of the yeast will flocculate. Cheers!