Comment 5 for bug 1716254

I have added the following CSS Style classes to Xpad.

XpadPad
XpadPadProperties
XpadPreferences
XpadTextView
XpadToolbar

Following your example, this CSS would color the complete pad.

textview.XpadTextView, text {
 color: #ffffff;
 background-color: #0000ff;
 background-image: none;
}

Would you mind to test this by the develepment branch?
This is how to obtain and test the branch.

Install bzr and development tools/packages, such as intltool, make, etc.
bzr branch lp:xpad (get a copy of the source code to your local system)
cd xpad
./autogen.sh
./configure
make
cd src
./xpad

If the version number in Xpad (Help -> About) is v5.1, you did it right. :-)