Is there any way to hide the menu but not the sidebars on tablets? It looks like that changing the values for sidebar-a or sidebar-b in the back-end (Templates: Edit Style | Layouts | Grid) does not affect the front-end at all.
Thanks a lot for the answer. I am not sure, but I think there is a bug in the CSS. When the html or body width is set to 1024 pixel (iPad landspace) the menu is above the content. In my opinion, the menu should be still on the left side. Also in the back-end (Extensions | Templates | Templates) the link to your website is wrong:
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