Issues with whitespace.el's default color scheme

[kj]

(My version of Emacs is 24.3.1, running in text mode, in a Terminal
window, on OS X Lion.)

While working on a plain tab-delimited file (in basic Fundamental-mode,
no highlighting/coloring of any kind) I decided to give whitespace.el
a try, to make empty cells visible.

Therefore, I evaluated

(require 'whitespace)

and then ran M-x whitespace-mode.

The whitespace characters have become visible, as advertised, but
in addition, to my surprise, the whole buffer has been colorized.
Now *all* the characters, not just those for whitespace, are shown
with new foreground and background colors.

This means that now the buffer appears in 3 colors: the new foreground
and background colors, plus the original background color (for the
locations on the screen where there are no characters).  Unfortunately,
I find this new color scheme too disturbing to work with.  (And
here, by "the new color scheme", I refer not only to two new
additional colors, but also to the fact that a screen location's
background color differs depending on whether it shows a character
or not.)

I would like to return the foreground and background colors to
their original values (which, BTW, I did not set explicitly: I have
been using the colors inherited by the Emacs session from the
Terminal window).

More precisely,

1. for non-whitespace characters, I want their foreground and
background colors to be *inherited* from whatever color they have
under the buffer's major mode when whitespace-mode is not active.

2. for whitespace characters, I want the foreground and background
colors to be inherited from the buffer's major mode's color scheme
for unhighlighted characters.

I've have not been able to find my bearings in the documentation
page and source code for whitespace.el.

If anyone knows how to do this, or has any other helpful suggestions,
please let me know.

TIA!

kj