id and class selectors
If you want to set CSS styles in HTML elements, you need to set "id" and "class" in the element Selector.
id selector
The id selector can specify a specific style for HTML elements marked with a specific id.
The HTML element uses the id attribute to set the id selector, and the id selector in CSS is defined with "#".
The following style rules apply to the element attribute id="para1":
Example
#para1 { text-align:center; color:red; }
The ID attribute should not start with a number. IDs starting with a number are browsed in Mozilla/Firefox does not work in the device.
class selector
class selector is used to describe the style of a group of elements. The class selector is different from the id selector. Class can be used in multiple elements.
The class selector is represented by the class attribute in HTML. In CSS, the class selector is displayed with a dot ".":
In the following example, all objects with the center class HTML elements are all centered.
p.center {text-align:center;}
The first character of the class name cannot use numbers! It won't work in Mozilla or Firefox.
【Related Recommendations】
1. Special Recommendation:"php Programmer Toolbox" V0.1 version Download
2. Free css online video tutorial
3. php.cn Dugu Jiujian (2)-css video tutorial
The above is the detailed content of Introduction to CSS Id and Class selectors. For more information, please follow other related articles on the PHP Chinese website!

@keyframesandCSSTransitionsdifferincomplexity:@keyframesallowsfordetailedanimationsequences,whileCSSTransitionshandlesimplestatechanges.UseCSSTransitionsforhovereffectslikebuttoncolorchanges,and@keyframesforintricateanimationslikerotatingspinners.

I know, I know: there are a ton of content management system options available, and while I've tested several, none have really been the one, y'know? Weird pricing models, difficult customization, some even end up becoming a whole &

Linking CSS files to HTML can be achieved by using elements in part of HTML. 1) Use tags to link local CSS files. 2) Multiple CSS files can be implemented by adding multiple tags. 3) External CSS files use absolute URL links, such as. 4) Ensure the correct use of file paths and CSS file loading order, and optimize performance can use CSS preprocessor to merge files.

Choosing Flexbox or Grid depends on the layout requirements: 1) Flexbox is suitable for one-dimensional layouts, such as navigation bar; 2) Grid is suitable for two-dimensional layouts, such as magazine layouts. The two can be used in the project to improve the layout effect.

The best way to include CSS files is to use tags to introduce external CSS files in the HTML part. 1. Use tags to introduce external CSS files, such as. 2. For small adjustments, inline CSS can be used, but should be used with caution. 3. Large projects can use CSS preprocessors such as Sass or Less to import other CSS files through @import. 4. For performance, CSS files should be merged and CDN should be used, and compressed using tools such as CSSNano.

Yes,youshouldlearnbothFlexboxandGrid.1)Flexboxisidealforone-dimensional,flexiblelayoutslikenavigationmenus.2)Gridexcelsintwo-dimensional,complexdesignssuchasmagazinelayouts.3)Combiningbothenhanceslayoutflexibilityandresponsiveness,allowingforstructur

What 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.

CSSanimationsarenotinherentlyhardbutrequirepracticeandunderstandingofCSSpropertiesandtimingfunctions.1)Startwithsimpleanimationslikescalingabuttononhoverusingkeyframes.2)Useeasingfunctionslikecubic-bezierfornaturaleffects,suchasabounceanimation.3)For


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

PhpStorm Mac version
The latest (2018.2.1) professional PHP integrated development tool

Dreamweaver CS6
Visual web development tools

ZendStudio 13.5.1 Mac
Powerful PHP integrated development environment

VSCode Windows 64-bit Download
A free and powerful IDE editor launched by Microsoft

WebStorm Mac version
Useful JavaScript development tools
