Issue, white line in the witdh of each page

[Lylo]

Hi crazy Talkgraphers !!

I have an issue in my web site, a white line appear without action from me on each page. Look the picture



In Xara webdesigner the line disappear, it's only in preview and online I see it.

Perhaps a error with the lenght page ? I have no problem with a single page in preview, no line, only in whole site, it is in "supersite" mode, in vertical scroll.