Apply a z-index value

In this lesson:

1. What is a z-index value?
2. Use a z-index value to stack elements

What is a z-index value?

The z-index value controls the stack order of an element. 

1. Elements with a higher z-index value stack on top of those with a lower value
2. Child elements can only stack according to their parent element. (i.e., If element A has a higher z-index than element B, the children of element B will never overlap element A)
3. Z-index only works on relative, absolute, and fixed positioning
4. Default z-index value is 0

Use a z-index value to stack elements

1. Select a div block you’d like to position
2. Apply a z-index value (because the default z-index value is 0, anything greater than 0 will position an element on top)
3. Higher values will stack on top of lower values
4. Negative values can cause elements to disappear

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