CSS Positioning Z-index problem

1. Some browsers under the level of the element to cover the existence of bugs;
   
   The z-index of an element is too large to be obscured at all times;
   
   JS dynamic calculation Z-index, resulting in the element coverage Relationship Department controllable

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   It can be understood that the location tree contains all the elements in the DOM tree that are not position staitc. Non-sibling element comparison hierarchies can be compared in this way:
   
   1. Traverse the parent node of the anchor tree up to 2 elements as sibling elements.
   
   2. The final comparison is based on the above conclusions. The higher-level elements will be closer to the user's monitor and can cover low-level elements.
   
   
   Example one: Assume that all red elements position are not static, and z-index=1, according to the above comparison rules can be known:
   
   1. C > (b && b *) > (a && A *) is the element C and C of all positioning element levels higher than A, b
   
   2. M > H, g > K, D > m
   
   Example two: Suppose that the position of a does not exist for the Static,z-index attribute, the child elements of a in the location tree Z-index once for 1,2,3,4 ... other positioning elements z-index:1:
   
   1. According to conclusion three: Ie6/7 B > (a && A *) that is, the level of element B is higher than the level of all positioning elements of a and a, other browsers: i > H > B > D reprint please indicate the source: CSS positioning z-index problem
   

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