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CSS Property

z-index

Positioning

Controls the stacking order of positioned elements.

Syntax

z-index: value;

Example

z-index: 10;

Common use cases

  • Keeping modals above page content
  • Dropdown menus over other elements
  • Layering background and foreground elements

Practical developer insight

z-index often fails because the element is inside a different stacking context. Properties like opacity, transform, or filter can silently create one — check your parent chain.

Related properties

positiondisplayopacity