问题
This seems to be a bug specific to firefox (version 7.0.1), I have copied the offending code into jsFiddle.
but jsFiddle DOES NOT REPRODUCE THE BUG. copy the code from jsFiddle into a blank html document and test it locally to see the issue.
http://jsfiddle.net/kCMeu/1/
This is the normal state of the menu items before you over over any of them:
This is the first sub_item when hovered over wiht the mouse:
And the third sub_item:
And now the last:
Where did that white margin come from around the #global_nav_box div? it only shows up on the hover state of the last sub item.
That is the bug I cant (conveniently) fix.
Fixes I've found are: Setting the body tag 'margin-top:0px' - but that leave an unsightly margin on the left and right of the page. Removing the 'z-index' property from the CSS for #global_nav_box - I thought i'd fixed it, until all the content on the page below scrolled over the div when you scroll on the page.
So why does it do this? Can you replicate this on Firefox? How can I fix it?
Thanks in advance.
Update: Ive had some of my friends test it and it (the bug) shows up for some and not for others, I have also tested in in Windows XP mode and it (the bug) still doesn't show up. All my testers were running Windows 7 and Firefox 7.0.1.
I've disabled all plugins and extensions on my install of Firefox and its still there. Insane.
回答1:
Although I do not know what caused this issue I have found a clean solution for it :)
Could you not wrap the absolute positioned div in a fixed div like this: http://jsfiddle.net/HelloJoe/JXWNj Source: HelloJoe
His solution from the previous thread that was the cause for this one fixed everything. :)
来源：https://stackoverflow.com/questions/7943585/fixed-positioning-bug-in-firefox-7-0-1-some-overflow-seems-to-cause-1px-margin