The value of the z-index attribute is negative, and the value of the z-index attribute is negative.

The value of the z-index attribute is negative, and the value of the z-index attribute is negative.

The value of the z-index attribute is negative:

In many CSS codes, we can see that the z-index attribute value is set to a negative number. The following describes the performance of a negative value. In general, as long as the object sets the position attribute and the attribute value is not static, this object can overwrite non-locating objects. The code example is as follows:

<! DOCTYPE html> 
In the above Code, element a can overwrite Element B and then look at a code example:
<! DOCTYPE html> 
The code above shows that element B can overwrite Element a. That is to say, elements in a normal document stream can overwrite objects with the position Attribute Set and the attribute value is not static, and the z-index value is negative.
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