How Does CSS z-index Control the Stacking Order of HTML Elements?
Understanding z-index Stacking Order
Positioning Elements with z-index
The z-index property in CSS determines the stacking order of positioned elements. Specifically, it dictates which elements appear in front of or behind others on the z-axis, which represents depth on a three-dimensional plane.
Effects on Positioned Elements
Z-index only works on elements with a position other than static (i.e., absolute, relative, fixed, or sticky). It does not affect elements with a position of static or elements positioned using floats.
Stacking Contexts
A stacking context is created when an element is positioned and has a z-index applied. Within a stacking context, the z-index property sets the stacking order of the positioned element and its descendants. Stacking contexts prevent elements in one context from interfering with the stacking order of elements in a different context.
Stacking Order Rules
The stacking order of elements without a z-index specified is as follows:
- Backgrounds and borders of the root element
- Non-positioned, non-floating block elements
- Non-positioned floating elements
- Inline elements
- Positioned elements
When a z-index property is applied, the stacking order is modified:
- Backgrounds and borders of the root element
- Positioned elements with a z-index of less than 0
- Non-positioned, non-floating block elements
- Non-positioned floating elements
- Inline elements
- Positioned elements with a z-index of 0
- Positioned elements with a z-index greater than 0
Examples of Stacking Order
Mixed Sibling Result: div.sibling-2 will appear in front of div.sibling-1 because its z-index is higher. Nested div.container has position: static and z-index: 0 Result: div.sibling will appear in front of both child divs because it is positioned with a higher z-index in a different stacking context. The above is the detailed content of How Does CSS z-index Control the Stacking Order of HTML Elements?. For more information, please follow other related articles on the PHP Chinese website! AI-powered app for creating realistic nude photos Online AI tool for removing clothes from photos. Undress images for free AI clothes remover Generate AI Hentai for free. Easy-to-use and free code editor Chinese version, very easy to use Powerful PHP integrated development environment Visual web development tools God-level code editing software (SublimeText3)
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