Vietnamese course text grabled

The PDF for the student text for basic course volume one seems a bit messed up.
The first page at the lesson 1 bookmark is an unusual shape (more landscape than portrait) and all the pages after are bigger or zoomed in more.
ANny ideas for how to fix that?
The first page at the lesson 1 bookmark is an unusual shape (more landscape than portrait) and all the pages after are bigger or zoomed in more.
ANny ideas for how to fix that?