MathJax menu occluded due to z-ordering

Created by: nageh

When the classic skin is used on Wikipedia the MathJax menu gets partially occluded by the toolbar on the left side, despite the HTML positioning element of the popup menu is assigned a high z-index. The reason for this is that the positioning element gets created as a child to the math formula's immediate parent rather than as a child to the HTML root element, so it cannot override the layering order because it is operating in a different stacking context. See also https://developer.mozilla.org/en/CSS/Understanding_z-index/The_stacking_context