MS Word: Bottom border runs off page when using numbered lists

Question

I'm formatting a manuscript in which all heading 1 styles (i.e. chapter headings) are automatically numbered, as in Chapter One, Chapter Two, etc. The chapter headings are right-aligned, italicized, and have a bottom border (i.e. a line that divides the chapter title from the body text), so that on the page, they look like this:

                          Chapter One
                        Chapter Title
-------------------------------------

(chapter text)
(chapter text)
(chapter text)
(chapter text)

                          Chapter Two
                        Chapter Title
-------------------------------------

(chapter text)

And so on.

But when I send this formatting to the printer, they tell me the bottom border is running off the page. Indeed, when playing around with the margins, I've discovered that the border sometimes extends past the margin, but not the page, so I can see it extend irregularly (sometimes a few millimeters, sometimes an inch). I've eliminated the automatic numbering and that seems to solve the problem, so that the border doesn't run at all past where it's supposed to stop. This leads me to believe that, when Word calculates the left-hand margin, it doesn't take into account the space for the numbers. Is there a way to make the border stop at the margin with the automatic numbering on?

I'm nto sure if this makes a difference, but the numbering is specified in a multilevel list and has the following options:

• Number alignment: Right
• Aligned at: 0"
• Text indent at: 0"
• Follow number with: Nothing

Thanks, everyone.