I would bet it is your resolution, specifically the width. In full screen at 1920x1080, I have no issues. But if I open IE in a window that is significantly less wide than the 1920 then I get the same effect, until scroll bars come into play. Almost like IE doesn't correctly figure the width of the sidebars and so it doesn't go with scroll bars until things overlap.
Is there a setting to be used when browsing the site with a cell phone? The borders as they are by default take quite a lot of space from that small screen estate available.
I'm not sure i follow you, BK. Which borders take a lot of space? What phone/browser are you using? Is there a way for you to take a screenshot and post it here?