This time I will bring you a detailed explanation of the use of the CSS cascading mechanism. What are the precautions for using the CSS cascading mechanism? Here are practical cases, let’s take a look.
Why is there a cascading mechanism in css
Because there may be multiple styles in css that affect a certain attribute of the same element at the same time , the cascading mechanism can resolve style conflicts between authors (people who write code), users (people who browse pages) and user agents (generally referred to as browsers).
Each style rule in the cascade has a weight value. When several of the rules take effect at the same time, the rule with the largest weight takes precedence. Generally speaking, the style weight value specified by the author is higher than the user style weight value, and the user style weight value is higher than the client (user agent) weight value. General weight value and object, whether there is! important, specificity is related to position. In the cascading order, the following weight values are from small to large
(1) User agent style
(2) User general style
(3) Author general style
(4) Author important style (!important)
(5) User important style (!important)
(6) If two styles come from the same code, such as both From the author (code), and their style declarations are equally important, they are calculated according to the specificity. The ones with high specificity will cover the
with low specificity (7) If the specificity is also the same, the further back The higher the priority of the style
Why the important styles set by the user have a higher priority than the important styles of the author? The reason for this is to facilitate the user to implement some special requirements, such as adjusting the page font size, etc. .
Calculation of selector specificity
(1) If a declaration appears in the style attribute of an element, then a Counted as 1;
(2)b is equal to the total number of all ID selectors in the selector and
(3)c is equal to all class selectors and attribute selectors in the selector, And the sum of the sum of the pseudo-class selectors
(4) d is equal to the sum of the sum of all label selectors and pseudo-element selectors in the selector
a-b-c-d is the selector Specificity, the comparison order starts from a first, and whoever is greater first will have a higher priority.
Note:
inheritance has the lowest priority and has no specificity
combining characters (eg, >) and The specificity of the universal selector (*) is 0
.box{} /*特异度=0,0,1,0*/ .box p{} /*特异度=0,0,1,1*/ #nav li{} /*特异度=0,1,0,1*/ p:first-line{} /*特异度=0,0,0,2*/ /*特异度=1,0,0,0*/
I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the PHP Chinese website!
Recommended reading:
Detailed analysis of webpack style loading
##20 CSS code usage precautions in front-end practical projects
The above is the detailed content of Detailed explanation of the use of CSS cascading mechanism. For more information, please follow other related articles on the PHP Chinese website!

In this post, Blackle Mori shows you a few of the hacks found while trying to push the limits of Cohost’s HTML support. Use these if you dare, lest you too get labelled a CSS criminal.

Custom cursors with CSS are great, but we can take things to the next level with JavaScript. Using JavaScript, we can transition between cursor states, place dynamic text within the cursor, apply complex animations, and apply filters.

Interactive CSS animations with elements ricocheting off each other seem more plausible in 2025. While it’s unnecessary to implement Pong in CSS, the increasing flexibility and power of CSS reinforce Lee's suspicion that one day it will be a

Tips and tricks on utilizing the CSS backdrop-filter property to style user interfaces. You’ll learn how to layer backdrop filters among multiple elements, and integrate them with other CSS graphical effects to create elaborate designs.

Well, it turns out that SVG's built-in animation features were never deprecated as planned. Sure, CSS and JavaScript are more than capable of carrying the load, but it's good to know that SMIL is not dead in the water as previously

Yay, let's jump for text-wrap: pretty landing in Safari Technology Preview! But beware that it's different from how it works in Chromium browsers.

This CSS-Tricks update highlights significant progress in the Almanac, recent podcast appearances, a new CSS counters guide, and the addition of several new authors contributing valuable content.

Most of the time, people showcase Tailwind's @apply feature with one of Tailwind's single-property utilities (which changes a single CSS declaration). When showcased this way, @apply doesn't sound promising at all. So obvio


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

SublimeText3 English version
Recommended: Win version, supports code prompts!

ZendStudio 13.5.1 Mac
Powerful PHP integrated development environment

Safe Exam Browser
Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.

SublimeText3 Chinese version
Chinese version, very easy to use

EditPlus Chinese cracked version
Small size, syntax highlighting, does not support code prompt function
