This problem is giving me an headache. I have website that is using Twitter Bootstrap’s classes navbar and .navbar-fixed-top. The idea is that navigation is fixed to the top and content scrolls under it. Background of the navigation is same as background of the site (subtle gray pattern).
The problem is that when you scroll little bit the pattern disappears partialy and tiny borders appear to the sides. This happens at least with Chrome and IE9.
there are two things i see. the first is that the nav has multiple backgrounds, the nav itself has a background and then the ul has the same background. the other thing is hard to tell but if you remove the flexslider the flickering of the nav is no longer an issue. so i think that the flexslider is the problem. as said before, the lines on the side is element-shadows.
the nav doesn’t have a background – the backgrounds are on the first child div and the ul (as you mention). The parent nav element is the only one that is full viewport width – so it should have the background. The shadows will then slide up behind the background.
Carl, which browser are you seeing the flicker in? I don’t see it FF, perhaps the OP doesn’t know about it.
Here is a screenshot of the problem (or two problems). First thing is that background kinda disappears from the .container it should have same background all the time. The second thing is the shadow (like TheDoc mentioned) of the other elements.
The shadow from the other elements (left arrow) will disappear if you put the background on nav.main. Firefox doesn’t show the other problem – I didn’t see until I tried in Chrome just now. I’m looking into it…