z-index
Positioning
Decides what stacks on top; the comparison only happens within one stacking context.
| How to write it | z-index: auto; |
|---|---|
| Common values | auto, 0, 10, -1 |
| Inherited | No — it stops at this element |
| Category | Positioning |
How to read this
- An inherited property only needs writing once on the parent — every child picks it up. Most text properties work this way.
- A shorthand resets whatever you leave out. Writing background: red alone also wipes a background image you set earlier.
- When rules collide, the more specific selector wins; only when specificity ties does source order decide.
- Animate transform and opacity for smoothness. Changing width or top forces the layout to be recalculated.
Frequently asked questions
Q. What is the CSS z-index property?
Decides what stacks on top; the comparison only happens within one stacking context.
Q. How do you write z-index?
As z-index: auto; Common values include auto, 0, 10, -1.
Q. Is z-index inherited?
No. It applies only where you write it, so each element needs its own declaration.
Q. What group does z-index belong to?
The positioning group.