Center aligning published lectora course.

I would like to know how users center align everything in their presentations, not simply the custom background image I made for my presentation.

I would like to create a content wrapper and simply control the wrappers alignment.. is this possible as lectora uses the body{background-image:""} style in the header?

I have input text fields and close buttons as well as various other navigation items I would like to simply wrap in a div container and position.

Thanks,

OTR-