Bojan,
This is not hard to do.
Open internet exporer and use the "file" "open" command to open the file "TournamentExport" (or "StatsExport").
Open the source file with "View" "Source".
Then just change the code for the background color to whatever you want it to be.
Then everytime you subsequently export a tournament summary or stats summary the background will be the new color.
So, it is a manual change, but you only have to do it once.