How Does CSS z-index Control the Stacking Order of HTML Elements?
Dec 25, 2024 am 03:47 AMUnderstanding 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! Undress images for free AI-powered app for creating realistic nude photos Online AI tool for removing clothes from photos. AI clothes remover Swap faces in any video effortlessly with our completely free AI face swap tool! 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)
Hot AI Tools
Undress AI Tool
Undresser.AI Undress
AI Clothes Remover
Clothoff.io
Video Face Swap
Hot Article
Hot Tools
Notepad++7.3.1
SublimeText3 Chinese version
Zend Studio 13.0.1
Dreamweaver CS6
SublimeText3 Mac version
Hot Topics

There are three ways to selectively include CSS on a specific page: 1. Inline CSS, suitable for pages that are not frequently accessed or require unique styles; 2. Load external CSS files using JavaScript conditions, suitable for situations where flexibility is required; 3. Containment on the server side, suitable for scenarios using server-side languages. This approach can optimize website performance and maintainability, but requires balance of modularity and performance.

Flexboxisidealforone-dimensionallayouts,whileGridsuitstwo-dimensional,complexlayouts.UseFlexboxforaligningitemsinasingleaxisandGridforprecisecontroloverrowsandcolumnsinintricatedesigns.

The HTML popover attribute transforms elements into top-layer elements that can be opened and closed with a button or JavaScript. Popovers can be dismissed a number of ways, but there is no option to auto-close them. Preethi has a technique you can u

CSS blocks page rendering because browsers view inline and external CSS as key resources by default, especially with imported stylesheets, header large amounts of inline CSS, and unoptimized media query styles. 1. Extract critical CSS and embed it into HTML; 2. Delay loading non-critical CSS through JavaScript; 3. Use media attributes to optimize loading such as print styles; 4. Compress and merge CSS to reduce requests. It is recommended to use tools to extract key CSS, combine rel="preload" asynchronous loading, and use media delayed loading reasonably to avoid excessive splitting and complex script control.

In the following tutorial, I will show you how to create Lottie animations in Figma. We'll use two colorful designs to exmplify how you can animate in Figma, and then I'll show you how to go from Figma to Lottie animations. All you need is a free Fig

We put it to the test and it turns out Sass can replace JavaScript, at least when it comes to low-level logic and puzzle behavior. With nothing but maps, mixins, functions, and a whole lot of math, we managed to bring our Tangram puzzle to life, no J

ThebestapproachforCSSdependsontheproject'sspecificneeds.Forlargerprojects,externalCSSisbetterduetomaintainabilityandreusability;forsmallerprojectsorsingle-pageapplications,internalCSSmightbemoresuitable.It'scrucialtobalanceprojectsize,performanceneed

No,CSSdoesnothavetobeinlowercase.However,usinglowercaseisrecommendedfor:1)Consistencyandreadability,2)Avoidingerrorsinrelatedtechnologies,3)Potentialperformancebenefits,and4)Improvedcollaborationwithinteams.
