国产av日韩一区二区三区精品,成人性爱视频在线观看,国产,欧美,日韩,一区,www.成色av久久成人,2222eeee成人天堂

Home Web Front-end CSS Tutorial Why Does Fixed Positioning Break Z-Index Ordering?

Why Does Fixed Positioning Break Z-Index Ordering?

Dec 20, 2024 am 04:53 AM

Why Does Fixed Positioning Break Z-Index Ordering?

Understand the Z-Index Paradox with Fixed Positioning

When dealing with HTML elements, the z-index property controls the stacking order, determining which element appears above or below others on the page. However, an unexpected behavior occurs when using z-index with elements positioned fixed and static.

Consider the following code snippet:

#over {
  width: 600px;
  z-index: 10;
}

#under {
  position: fixed;
  top: 5px;
  width: 420px;
  left: 20px;
  z-index: 1;
}

You would expect the element with #over to be displayed behind #under since it has a higher z-index value. However, the fixed element (#under) will stubbornly overlay #over, ignoring its supposed lower priority.

This is because fixed positioning removes an element from the normal document flow. It positions the element based on the viewport, essentially creating a separate layer on top. As a result, the z-index of fixed elements doesn't interact with the z-index of non-fixed elements.

To rectify this issue and allow #over to appear behind #under, add position: relative; to #over:

#over {
  width: 600px;
  z-index: 10;
  position: relative;
}

This small adjustment establishes a new local stacking context within #over, enabling its z-index to influence elements within that context. Now, #under will display correctly behind #over, respecting the intended stacking order.

Remember, fixed positioning is a powerful tool for creating absolute positioning on the page, but it comes with limitations when interacting with z-index in certain scenarios. By applying the position: relative trick, you can regain control over the stacking order and achieve your desired layering effects.

The above is the detailed content of Why Does Fixed Positioning Break Z-Index Ordering?. For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undress AI Tool

Undress AI Tool

Undress images for free

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

What is 'render-blocking CSS'? What is 'render-blocking CSS'? Jun 24, 2025 am 12:42 AM

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.

What is Autoprefixer and how does it work? What is Autoprefixer and how does it work? Jul 02, 2025 am 01:15 AM

Autoprefixer is a tool that automatically adds vendor prefixes to CSS attributes based on the target browser scope. 1. It solves the problem of manually maintaining prefixes with errors; 2. Work through the PostCSS plug-in form, parse CSS, analyze attributes that need to be prefixed, and generate code according to configuration; 3. The usage steps include installing plug-ins, setting browserslist, and enabling them in the build process; 4. Notes include not manually adding prefixes, keeping configuration updates, prefixes not all attributes, and it is recommended to use them with the preprocessor.

What is the conic-gradient() function? What is the conic-gradient() function? Jul 01, 2025 am 01:16 AM

Theconic-gradient()functioninCSScreatescirculargradientsthatrotatecolorstopsaroundacentralpoint.1.Itisidealforpiecharts,progressindicators,colorwheels,anddecorativebackgrounds.2.Itworksbydefiningcolorstopsatspecificangles,optionallystartingfromadefin

CSS tutorial for creating a sticky header or footer CSS tutorial for creating a sticky header or footer Jul 02, 2025 am 01:04 AM

TocreatestickyheadersandfooterswithCSS,useposition:stickyforheaderswithtopvalueandz-index,ensuringparentcontainersdon’trestrictit.1.Forstickyheaders:setposition:sticky,top:0,z-index,andbackgroundcolor.2.Forstickyfooters,betteruseposition:fixedwithbot

What is the scope of a CSS Custom Property? What is the scope of a CSS Custom Property? Jun 25, 2025 am 12:16 AM

The scope of CSS custom properties depends on the context of their declaration, global variables are usually defined in :root, while local variables are defined within a specific selector for componentization and isolation of styles. For example, variables defined in the .card class are only available for elements that match the class and their children. Best practices include: 1. Use: root to define global variables such as topic color; 2. Define local variables inside the component to implement encapsulation; 3. Avoid repeatedly declaring the same variable; 4. Pay attention to the coverage problems that may be caused by selector specificity. Additionally, CSS variables are case sensitive and should be defined before use to avoid errors. If the variable is undefined or the reference fails, the fallback value or default value initial will be used. Debug can be done through the browser developer

CSS tutorial focusing on mobile-first design CSS tutorial focusing on mobile-first design Jul 02, 2025 am 12:52 AM

Mobile-firstCSSdesignrequiressettingtheviewportmetatag,usingrelativeunits,stylingfromsmallscreensup,optimizingtypographyandtouchtargets.First,addtocontrolscaling.Second,use%,em,orreminsteadofpixelsforflexiblelayouts.Third,writebasestylesformobile,the

How to create an intrinsically responsive grid layout? How to create an intrinsically responsive grid layout? Jul 02, 2025 am 01:19 AM

To create an intrinsic responsive grid layout, the core method is to use CSSGrid's repeat(auto-fit,minmax()) mode; 1. Set grid-template-columns:repeat(auto-fit,minmax(200px,1fr)) to let the browser automatically adjust the number of columns and limit the minimum and maximum widths of each column; 2. Use gap to control grid spacing; 3. The container should be set to relative units such as width:100%, and use box-sizing:border-box to avoid width calculation errors and center them with margin:auto; 4. Optionally set the row height and content alignment to improve visual consistency, such as row

CSS tutorial for creating loading spinners and animations CSS tutorial for creating loading spinners and animations Jul 07, 2025 am 12:07 AM

There are three ways to create a CSS loading rotator: 1. Use the basic rotator of borders to achieve simple animation through HTML and CSS; 2. Use a custom rotator of multiple points to achieve the jump effect through different delay times; 3. Add a rotator in the button and switch classes through JavaScript to display the loading status. Each approach emphasizes the importance of design details such as color, size, accessibility and performance optimization to enhance the user experience.

See all articles