Detailed explanation of the usage of position attribute in CSS
This article introduces the usage, classification and usage effect display of the position attribute in CSS. I hope it will be helpful to friends who are learning CSS!
Detailed explanation of the usage of position attribute in CSS
1. What is the role of position attribute?
The CSS position property is used to specify how an element is positioned in the document. The top, right, bottom and left attributes determine the final position of the element. (MDN definition).
(Recommended learning: CSS tutorial)
2. What are the classifications of position?
1, static
Normal layout behavior, the current layout position of the element in the regular flow of the document. At this time the top, right, bottom, left and z-index properties have no effect.
The position remains unchanged.
2, relative
Under this keyword, the element is first placed at the position when no positioning is added, and then the position of the element is adjusted without changing the page layout (therefore, the element will be placed where the positioning is not added). Leave the location blank when adding targeting). position:relative is not valid for table-*-group, table-row, table-column, table-cell, table-caption elements.
Offset relative to its own position.
3. Absolute
Does not reserve space for the element, and determines the position of the element by specifying the offset of the element relative to the nearest non-static positioned ancestor element. Absolutely positioned elements can have margins set and will not be merged with other margins.
As if this element never existed, the offset of the element will be determined based on the non-static ancestor elements of this element.
4, fixed
Does not reserve space for elements, but specifies the position of the element by specifying its position relative to the screen viewport (viewport). The element's position does not change when the screen scrolls. When printing, the element will appear at a fixed location on each page. The fixed attribute creates a new stacking context. When the transform attribute of an element's ancestor is non-none, the container is changed from the viewport to that ancestor.
Lower versions of IE are not compatible.
5, sticky
The box position is calculated according to the normal flow (this is called the position in the normal flow), and then relative to the flow root (BFC) and containing block (of the element in the flow) nearest block-level ancestor). In all cases (even when the positioned element is a table), the positioning of this element does not affect subsequent elements. When element B is sticky positioned, the position of subsequent elements is still determined by the position of B when it was not positioned. position: sticky has the same effect as position: relative on table elements.
At the same time, sticky has the following problems:
1. Sticky will not trigger BFC.
2. The style sheet z-index is invalid. Writing style inline is valid.
3. Sticky is container-related, which means that the sticky feature will only take effect in the container it is in. This point is emphasized because in actual use, when the body is set to height: 100%, the sticky element stops at a certain position.
3. Test code
The public code of the test code is as follows:
<html html>
<head>
<meta charset="utf-8">
<title>position</title>
</head>
<style>
.main-app{
display: flex;
justify-content: center;
align-items: center;
}
.app-container {
width: 100%;
height: 300px;
display: flex;
justify-content: center;
align-items: center;
}
#the-box{
position: static;
/* position: relative;
top:100px;
left:200px; */
}
.sub-box {
width: 50px;
height: 50px;
}
</style>
<body>
<div class="main-app">
<div class="app-container">
<div class="sub-box" style="background: gray;"></div>
<div id="the-box" class="sub-box" style="background: green;"></div>
<div class="sub-box" style="background: yellow;"></div>
<div class="sub-box" style="background: red;"></div>
</div>
</div>
</body>
</html>I selected the second element as our test object this time , the test environment is chrome 75 version.
1, static
#the-box{
position: static;
}Result:
Normal document flow display
2, relative
#the-box{
position: relative;
top:100px;
left:200px;
} Result:
The set position is offset from its original position, but the original position is retained.
3, absolute
#the-box{
position: absolute;
top: 100px;
left: 200px;
}Result:
The original fixed position is occupied by other elements, because the parent element is non-static (flex ), so the current element is offset by the set position relative to the parent element.
4. sticky
You must specify one of the four thresholds top, right, bottom or left before sticky positioning can take effect. Otherwise the behavior is the same as relative positioning.
This feature is that the position of the element is fixed in the viewport. If the page does not have a scroll axis, the feature will not be displayed. At this time, we slightly change its parent element to make the page appear with a scroll axis.
.app-container {
width: 100%;
height: 3000px;
display: flex;
justify-content: center;
align-items: center;
}
#the-box{
position: sticky;
top: 100px;
}Result:
When we scroll the page and the element is more than 100px from the top, the current element position relative to the viewport remains unchanged when scrolling down. This feature can be used as a fixed table header.
5, fixed
cannot be used for versions below IE7. In fact, it is equivalent to fixing the position of the element in the browser window.
#the-box{
position: fixed;
top: 100px;
left: 200px;
}Result:
No matter how you scroll the scroll axis, the element position always remains the same.
6、inherit
Specifies that the value of the position attribute should be inherited from the parent element.
7, initial
The initial keyword is used to set CSS properties to their default values and can be applied to any CSS style. (IE does not support this keyword)
8, unset
As the name suggests, the unset keyword can be simply understood as not setting. Actually, it is a combination of keywords initial and inherit.
When we set unset to a CSS property:
If the property is a default inherited property, the value is equivalent to inherit
If the property is a non-inherited property, the value Equivalent to initial
9, revert
is not yet included in the specification.
The above is the detailed content of Detailed explanation of the usage of position attribute in CSS. For more information, please follow other related articles on the PHP Chinese website!
Orbital Mechanics (or How I Optimized a CSS Keyframes Animation)May 09, 2025 am 09:57 AMWhat does it look like to refactor your own code? John Rhea picks apart an old CSS animation he wrote and walks through the thought process of optimizing it.
CSS Animations: Is it hard to create them?May 09, 2025 am 12:03 AMCSSanimationsarenotinherentlyhardbutrequirepracticeandunderstandingofCSSpropertiesandtimingfunctions.1)Startwithsimpleanimationslikescalingabuttononhoverusingkeyframes.2)Useeasingfunctionslikecubic-bezierfornaturaleffects,suchasabounceanimation.3)For
@keyframes CSS: The most used tricksMay 08, 2025 am 12:13 AM@keyframesispopularduetoitsversatilityandpowerincreatingsmoothCSSanimations.Keytricksinclude:1)Definingsmoothtransitionsbetweenstates,2)Animatingmultiplepropertiessimultaneously,3)Usingvendorprefixesforbrowsercompatibility,4)CombiningwithJavaScriptfo
CSS Counters: A Comprehensive Guide to Automatic NumberingMay 07, 2025 pm 03:45 PMCSSCountersareusedtomanageautomaticnumberinginwebdesigns.1)Theycanbeusedfortablesofcontents,listitems,andcustomnumbering.2)Advancedusesincludenestednumberingsystems.3)Challengesincludebrowsercompatibilityandperformanceissues.4)Creativeusesinvolvecust
Modern Scroll Shadows Using Scroll-Driven AnimationsMay 07, 2025 am 10:34 AMUsing scroll shadows, especially for mobile devices, is a subtle bit of UX that Chris has covered before. Geoff covered a newer approach that uses the animation-timeline property. Here’s yet another way.
Revisiting Image MapsMay 07, 2025 am 09:40 AMLet’s run through a quick refresher. Image maps date all the way back to HTML 3.2, where, first, server-side maps and then client-side maps defined clickable regions over an image using map and area elements.
State of Devs: A Survey for Every DeveloperMay 07, 2025 am 09:30 AMThe State of Devs survey is now open to participation, and unlike previous surveys it covers everything except code: career, workplace, but also health, hobbies, and more.
What is CSS Grid?Apr 30, 2025 pm 03:21 PMCSS Grid is a powerful tool for creating complex, responsive web layouts. It simplifies design, improves accessibility, and offers more control than older methods.
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Dreamweaver Mac version
Visual web development tools
SAP NetWeaver Server Adapter for Eclipse
Integrate Eclipse with SAP NetWeaver application server.
SublimeText3 Chinese version
Chinese version, very easy to use
MantisBT
Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.
DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software
