gadams,

That's because the browser has its own set of font sizes. The browser uses
the nearest available size. If you use 9 in Publisher it will show as 8; if
you use 11 it will show as 10 etc...

If you MUST have the text to appear exactly the way you designed it, insert
a very short line of the same colour as the background in an empty space of
the text frame. The size will stay as you see it in the Pub document, but it
won't be a text, it'll be a graphic. It's a question of choice.