See attached, this is 6.3 on Safari.
Check the link: http://foundation.zurb.com/sites/docs/sticky.html
I'm pretty sure this was introduced in 6.3.

@anselmdk I can't reproduce. Did the page load like that or did you have to do some scrolling or window resizing in order to make it happen?
It happens as soon as you scroll down. I'm on Safari 9.0.3 on El Capitan. Maybe that's the issue.
Me also was unable to reproduce the bug! Seems like a YAII unless there is something to do with the browser support
Okay, I just checked on Browserstack in MacOS Sierra, which comes bundled with Safari 10, and I can't reproduce there, so it seems to be specific to Safari 9. Maybe it's time for me to upgrade.
@anselmdk thanks for checking! I'm on 10.0.3 on El Capitan. So ya, Safari 9 it is.
@kball should we just close this and chalk it up as a Safari bug? Not sure what protocol is for this kind of situation.
Foundation ( specially JS ) is only supported for last two versions of safari so this should be closed!!
Well 9 is the second newest version of Safari (see here, but I agree that given that it works on latest Safari I'd not spend too much time on it.
@anselmdk Yeah just checked it .... sorry i use Linux ...... and so got confused a bit .... sorry about that !
@anselmdk is it possible for you to upgrade to 9.1.3 and test it? Not sure if the app store will make you jump to 10 or allow you to update to the latest version of 9. If that's a hassle or it doesn't work from the app store, don't worry about it.
@colin-marshall I checked, I'll need to run a system update for the safari upgrade, I think. I'll do that when I've got a free moment.
Just upgraded to Safari 9.1.2 and the bug persists. No idea why I had no option of upgrading to 9.1.3. Next option is 10.0.3 which I'll run now. It'll probably make the bug disappear.
Back up. As expected the bug doesn't persist on Safari 10.0.3.
Thanks for the updates @anselmdk. We're actually rewriting sticky for 6.4 so I think we'll probably just end up closing this issue but I'll wait for @kballl to weigh in on it first.
Let's not close in case until we have the 6.4 rewritten in case someone wants to submit a patch fix for this.
Closing as Safari 12.1.2 is the latest version now.
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Okay, I just checked on Browserstack in MacOS Sierra, which comes bundled with Safari 10, and I can't reproduce there, so it seems to be specific to Safari 9. Maybe it's time for me to upgrade.