Some predefined table stylings might be unexpected or even wrong about pressbooks-book

[greatislander]

See also: http://alistapart.com/article/web-typography-tables

[SteelWagstaff]

Examples above from Clarke -- may exist in other themes as well.

[mcgratay]

So the Buckram default is:

This holds true for all supported formats: EPUB, MOBI, PDF, digital PDF, webbook.

The above tables all technically meet the expected behavior for their class, but I agree that having a redundant class doesn't make much sense and that ideally the "No Lines" class could be changed to remove the lines from the top and bottom of the table.

That being said, there is some variation in the table styles among different themes, even those which have been converted to Buckram. Finding out exactly which themes and formats are affected will take further research.