zMtLlC: I don't see the gaps on my system, at any zoom level. If the lines don't appear in printouts, the issue on your system may just be a display artefact. Updating your display drivers may resolve the matter. If the lines do appear in printouts, the issue on your system may be due to the printer driver, which Word uses for the page formatting. Updating your printer drivers may resolve the matter.

tfa91: Office 2013 uses a different document layout engine, so your results may not be directly comparable. Even so, updating your driver(s) may resolve the matter on your system too.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]