level 1 , 2 , 3 , 4 in W3C for CSS specifications

imahdio commented 2 years ago

I'm studying CSS specifications and the W3C lesson from CSS Essential Training course.

as you could see there is one contradictory condition in above attached image

it says

The first two versions of CSS, Level 1 and Level 2, published all the specification as one whole document.

in my point of view , it means level 1 related to CSS version 1 and level 2 related to CSS version 2. or in another section of above attached image , instructor said:

You may see some marked as Level 3 if it's an update from CSS2.

it means levels have some kind of relationship with version of css.

but in another section the instructor says:

levels have no relations with the version of css

Here are the questions:

do you belive there are 2 claims opposite with each other? why did it occure and what's your opinion about it?
what's the meaning of level 1 , level 2 and level 4 in front of each module in THIS W3C RESOURCE?
which meaning conveys when a module doesn't include any level?

MRGHOSJ commented 2 years ago

CSS1 The goal of the work on CSS1 has been to create a simple style sheet mechanism for HTML documents. The current specification is a balance between the simplicity needed to realize style sheets on the web, and pressure from authors for richer visual control.

CSS1 offers:

visual markup replacement: HTML extensions, e.g. "CENTER", "FONT" and "SPACER", are easily replaced with CSS1 style sheets. nicer markup: instead of using "FONT" elements to achieve the popular small-caps style, one declaration in the style sheet is sufficient. various integration levels: CSS1 style rules can be fetched from external style sheets, included in the 'STYLE' element, or put into 'STYLE' attributes. The latter option offers easy transition from HTML extensions. new effects: some new visual effects have been added to offer users new toys. The typographical pseudo-elements and the extra values on the background property fall into this category. scalability: CSS1 will be useful on equipment ranging from text terminals to high-resolution color workstations. Authors can write one style sheet and be reasonably sure that the intended style will come across in the best possible manner.

CSS1 does not offer:

per pixel control: CSS1 values simplicity over level of control, and although the combination of background images and styled HTML is powerful, control to the pixel level is not possible. author control: the author cannot enforce the use of a certain sheet, only suggest a layout language: CSS1 does not offer multiple columns with text-flow, overlapping frames etc. a rich query language on the parse tree: CSS1 can only look for ancestor elements in the parse tree, while other style sheet languages (e.g. DSSSL) offers a full query language.

CSS2 CSS2 includes all the power of CSS1, and adds enhancements in several areas to make the Web more appealing for both content providers and users.

CSS2 offers: CSS2 offers precise control over the presentation of Web pages. The ability to position elements explicitly greatly enhances control of document layout, both on screen and in print. Relatively positioned elements are shifted, by an amount specified by the designer, from the position they would have occupied in normal flow. Absolutely positioned elements are taken out of the normal flow of text entirely, and can be placed elsewhere to create navigation bars, indexes, and similar features. Floated elements can be used to place text or graphics in the margins, with text flowing around the floated element.

CSS2 has a rich WebFonts capability, offering dynamic download of fonts from a Web site (just as images are downloaded today). The fonts can be locked to a particular Web site and are not installed on the client machines. WebFonts also includes the information needed to synthesize fonts or to select similar looking fonts on the client, if the fonts specified by the designer are not available.

CSS selectors, which determine what style rules are applied to which parts of the document, have been made more powerful in CSS2. This gives designers greater flexibility and expressive power, particularly when styling XML documents.

CSS2 has the following main features: Aural Style Sheets: New style properties for defining the aural style sheet for documents. Paging:Definition of how pages need to be displayed or printed. This made cropping, registering marks and other layout features possible. Media Types: Different style rules for different types of media was introduced in CSS2. International Accessibility Features: More list styles were available for international documents. This included bidirectional text support as well as language sensitive quotation marks. Font: More fonts were defined and available for use. Positioning: CSS2 introduced the relative, absolute positioning and the placement determination within a document. This really helped the continuous media. Cursors: CSS2 defined the manner in which the cursor would respond to various actions.

CSS3 CSS3 does not deprecate older CSS code because it is only an addition to the features offered by CSS1. CSS3 allows developers to style HTML elements easier. They are less dependent on image files and can complete CSS styling with fewer lines of code. The aim of CSS1 was for appearance formatting, and it did not allow responsive designs.

CSS3 offers: Box Shadow One of the CSS3 new features is the box-shadow property that adds a shadow to an element. Instead of using multiple images around an item, this property lets you add shadow with a short line of code.

Opacity One of the CSS3 properties called opacity makes elements see-through or completely transparent. For instance, you can apply opacity to images or other HTML elements. The transparency level depends on the indicated values.

Rounded Corners Before the release of CSS3, developers had to write long code to produce rounded corners. Now, it is enough to apply the border-radius CSS3 property to HTML elements.

Attribute Selectors CSS3 also introduced new selectors in addition to the ones in CSS2. Instead of applying IDs or classes for styling, developers can select HTML elements according to their attributes.

As a result, you do not have to create unique IDs only to apply CSS rules.

New Colors One of the CSS3 features is the addition of new colors:

RGBA HSL HSLA Gradient Colors More than Web-Safe Fonts Instead of only using fonts labeled as web-safe, developers now can apply more unique fonts in their HTML documents. Before that, CSS wanted to ensure that all browsers and machines display fonts the same.

CSS3 Features: Useful Tips CSS3 supports responsive designs and manages media queries (used for determining users' devices and screen sizes). Since CSS3 new features let you produce fewer lines of code, you can boost the website speed. Since CSS3, CSS animations move without JavaScript or Flash code.

for more information visit this What is CSS4?

Daniel001-odii commented 2 years ago

Of course the levels has no relation with the version of CSS Let us take the levels as sub of the versions released. In each version of CSS theres a level up as i will call it and that's why the word level is used. That level up is now the level 1, 2,3 ... in turn. As you would observe at each level up new things were added plus different upgrades made, different features committed. For example: The addition of new colors like HSL, RGB is a level up to the normal and plain CSS3.

Airydev001 commented 2 years ago

Css level 1 which is term CSS 1 is the outdated version of Css in W3C CSS 2 also has specification than CSS 1 but CSS 3 is the latest version of Cascading Style Development. There is lot of limitation to this CSS so the need for improvement in web technology brings about new evolution of CSS level every level has its own capability for CSS3 we have something called properties and modules CSS 2 Support singe styling modules but CSS3 is break down to different modules for simplicity. There is something called external styling in CSS 3 but CSS 2 and CSS 1 can't have this. When it comes to different browser switching and compatibility CSS 2 and level cannot offer this..CSS4 is another level for more functions and modules upgrading.

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