Inkscape/.pdf question

[merman]

Whenever I convert in Inkscape to .pdf my valley/mountain fold lines have very thin light grey lines udnerneath them, visible on a grey (colored) background.

The strange thing is: this only shows on Acrobat. When I look at my .pdf-files on my Macbook or iPhone I don't see these lines... I have used several computers with Acrobat reader and they all seem to have the same problem...

Very often when I print from Acrobat Reader the grey lines are printed also. Does anyone know what causes this and how to convert to .pdf without these ugly lines?

For an example: see the X-Mas book. My kiwi is in there...

[TheRealChris]

use the search function.