View issue header is positioned incorrectly under various scrolling-related scenarios

Concerning the view issue header:

• In IE8, maximised at 1024x768 resolution, a horizontal scrollbar appears when the header transitions from scrolling (header-scrolling.png) to fixed (header-fixed.png).
• In all browsers, the header's background overlays the page border (header-overflow.png)
• In all browsers, the header does not move when the page is scrolled horizontally (viewissue-stalker.mp4).