I can reproduce the issue using the "Print preview" on Firefox and on
IE, on the tutorial and on other pages as well.
The Doc has a couple of print rules at the end of
http://docs.python.org/_static/basic.css and they look correct (and they
are also W3C valid). While I was trying to debug the problem using the
Web Developer plug-in of Firefox and the "Edit CSS" option the problem
disappeared without changing anything.
This is quite weird and lead me to think that there could be a priority
problem (even if I can't see any other rule that overrides the print rules).

Possible solutions could be:
1) add a couple of !important in the print rules;
2) move the print rules somewhere else;
3) create a distinct print CSS where to put all the print rules.