If the brain is not attached to anything in the skull how does it stay in place?

First thing, it is not as if the brain is not attached to
anything in the skull. The brain is attached to the spinal chord. Thus it is not freely
floating or hanging in the skull. Second there are many different layers of protective
covering between the brain and the skull that cushion and hold the brain in position.
This covering called meninges consists of three layers named dura matter, arachnoid, and
delicata pia. In addition , a clear liquid called cerebrospinal fluid separates the pia
mater and the arachnoid, and provides a a cushioning between the soft tissues of the
brain and the hard bones of the skull.