Add-on popup is positioned out of browser window bounds

[heitoragm]

Describe the bug Add-on popups are been placed out of browser window, making it only possible to click on accept button which is still inside of window bounds.

Expected behavior The add-on popups should be visible and interactive inside of browser window.

Screenshots

I don't know if I get it right but it seems like the popups are trying to position near the Extensions menu, which is hidden. I don't know either if this only happens in my environment but I'm leaving it here anyway. I could fix this by editing the chrome/includes/cascade-config.css file and adding the following line at 111:

/* Fixes Popups position when Extensions Menu Icon is hidden */
#notification-popup { margin: 1em -30em !important; }

Here's the result:

And that was the outcome:

By the way, that's a great project and sorry about my English skills.