I don't know if the code is wrong but if you're asking if the *result* of join is wrong, I don't think it is. It references the same file as these commands:
cd /static
cat /styles/largestyles,css
I agree it might be confusing but it's pretty explicitly documented. On the other hand, this is also documented and it's wrong by the above standard
>>> os.path.join(r'c:\abc', r'\def\g') # Windows paths
'\\def\\g'
On Windows \def\g is a drive-relative path not an absolute path. To get the right result you need to do:
>>> drive, path = os.path.splitdrive(r'c:\abc')
>>> drive + os.path.join(path, r'/def/g')
'c:/def/g'
This works even on systems that don't use drive letters. It would be nice if there was a less clumsy way to do this. It's worse than that because it also screws up UNC paths
>>> os.path.join(r'\\abc\def\ghi', r'\x\y')
'\\x\\y'
The result references a UNC share of \\x\y rather than a directory of x which is also wrong. It would be nice if there was a simpler way to get this right:
>>> os.path.join(r'c:\abc', r'\x\y', keep_drive_unc=True)
'c:\\x\\y'
>>> os.path.join(r'\\abc\def\ghi', r'\x\y', keep_drive_unc=True)
'\\\\abc\\def\\x\\y'