I think parts of the Navajo Nation does observe DST.

This is correct. Additionally, the Hopi Reservation, an enclave within the Navajo Nation, does not observe DST, hence the smaller shaded region.

There is also a Navajo enclave within that Hopi reservation/enclave: http://mm.icann.org/pipermail/tz/2016-May/023665.html

Oh wow. It's really cool that the developers put the effort in to denoting the difference.

Thank you!

The map actually simplifies the situation significantly. There are two Hopi enclaves within the Navajo Nation, the larger of which has a Navajo enclave nested within it.

Because of all this, you can travel less than 100 miles in a straight line and have to change your clock six times...