When checking format information of styles defined in CSS, when in your
browser, make sure you are on document layout when pressing NVDA+f. I refer
to a message I sent to this list a few days ago, asking that when in a
virtual rendered window, such as in browsers, that document review is
triggered by default when selecting text with NVDA+F9 and F10, as well as
when checking format information with NVDA+F.

Checking format info when screen review or object review is active reports
the wrong information.

The extent to which the below message is correct, is that all Windows screen
readers will report information in a top to bottom layout. This, for
example, does not give a true reflection of screen layout. A typical example
is the navigation bar which could be placed on the left side of the screen,
regardless of where one is on the page, at least, visually. According to
sscreen readers the navigation bar is always at the top. The best way to
determine actual screen layout is with a tablet, moving your finger across
the screen to see where elements are placed.