Parashas Tetzaveh · Passuk 29:6
Chabad.org — English translation + Rashi
Torah Temimah points to Yoma 19a (verified).
English: A baraita teaches that the priest’s hair was visible between the tzitz and the mitznefes; that was where he placed his tefillin.
In context: See the cited source for the full section.
Derash on the verse.
The placement of the tzitz and mitznefes left the forehead area used for the tefillin of the priest visible and unobstructed.