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CSS3

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CSS3 là sự phát triển mới nhất của ngôn ngữ Cascading Style Sheets và nhằm mở rộng CSS2.1. Nó mang đến rất nhiều điều mới mẻ đã được mong đợi từ lâu, như bo tròn góc , đổ bóng, gradients, transitions hoặc animations, cũng như các loại layout mới như multi-columns, flexible box hoặc grid layout. Các phần thử nghiệm có vendor-prefix và nên hoặc là tránh sử dụng trong môi trường production, hoặc là được sử dụng hết sức thận trọng khi cả cú pháp và semantic (ngữ nghĩa) của chúng có thể thay đổi trong tương lai.

Các Module và quá trình tiêu chuẩn hóa

CSS Level 2 đã cần 9 năm, từ tháng Tám 2002 tới tháng Sáu 2011 để đạt trạng thái Recommendation.  Điều này là do thực tế rằng một vài tính năng phụ kéo lại toàn bộ đặc tả kỹ thuật. Để đẩy nhanh tiến độ tiêu chuẩn hóa của các tính năng không quan trọng, CSS Working Group của W3C, trong một quyết định gọi là học thuyết Beijing, đã chia CSS thành các phần nhỏ hơn được gọi là các module . Mỗi một module bây giờ là một phần độc lập của ngôn ngữ và tiến thẳng lên tiến trình chuẩn hóa theo tốc độ của riêng nó. Trong khi một vài module đã thực sự được W3C khuyên dùng, một số khác vẫn đang là các bản dự thảo. Các module mới cũng được thêm khi có nhu cầu mới được xác định.

CSS Modules and Snapshots as defined since CSS3 Chính thức thì, không có tiêu chuẩn CSS3 per se . Mỗi module được tiêu chuẩn hóa một cách độc lập, chuẩn CSS bao gồm CSS2.1 đã được bổ sung và mở rộng bởi các module đã hoàn thiện, không nhất thiết tất cả cùng một cấp độ. Tại mỗi thời điểm, một snapshot của chuẩn CSS có thể được định nghĩa, bằng việc liệt kê CSS2.1 và các module trưởng thành.

Tổ chức W3 định kỳ xuất bản các snapshot như vậy, như năm 2007 hoặc 2010.

Do ngày nay không module nào với một level lớn hơn 3 được chuẩn hóa, điều này sẽ thay đổi trong tương lai. Một vài module, như Selectors 4 hoặc CSS Borders and Background Level 4 thực sự có một Editor's Draft, mặc dù chúng chưa đạt đến tình trạng First Published Working Draft.

Trạng thái các CSS module

Stable modules

Một vài CSS module là thực sự khá ổn định và đã đạt đến một trong ba mức độ khuyến nghị của CSSWG: Candidate Recommendation, Proposed Recommendation hoặc Recommendation. Chúng có thể được sử dụng không cần prefix và khá là ổn định, mặc dù một vài tính năng vẫn có thể bị loại bỏ ở giai đoạn Candidate Recommendation.

Các module này mở rộng cải thiện chỉ dẫn kỹ thuật CSS2.1 cái mà xây dựng nên lõi của chỉ dẫn kỹ thuật. Cùng với nó, chúng là snapshot hiện tại của chí dẫn kỹ thuật CSS.

CSS Color Module Level 3 Recommendation từ ngày 7 tháng Sáu, 2011

Thêm thuộc tính opacity, và các function hsl(), hsla(), rgba(), rgb() để tạo các giá trị <color>. Nó cũng định nghĩa từ khóa currentColor như là một màu hợp lệ.

Màu transparent bây giờ là một màu thực sự (cảm ơn sự hỗ trợ cho kênh alpha) và bây giờ là tên gọi khác cho rgba(0,0,0,0.0) .

Nó phản đối các từ khóa màu sắc hệ thống cái mà không nên được sử dụng trong môi trường production.

Selectors Level 3 Recommendation từ ngày 29 tháng Chín, 2011

Thêm:

The next iteration of the Selectors specification is already in progress, though it still hasn't reached the First Public Working Draft stage.

CSS Namespaces Module Recommendation since September 29th, 2011

Adds the support for the XML Namespaces by defining the notion of CSS qualified name, using the ' | ' syntax and adding the @namespace CSS at-rule.

Media Queries Recommendation since June 19th, 2012

Extends the former media type ( print, screen, ) to a full language allowing queries on the device media capabilities like only screen and (color) .

Media queries are not only used in CSS document but also in some attributes of HTML Elements, like the media attribute of the <link> element.

The next iteration of this specification is in the work, allowing to tailor a Web site regarding the input methods available on the user agent, with new media features like hover or pointer. Detection of EcmaScript support, using the script media features is also proposed.

CSS Style Attributes Recommendation since November 7th, 2013
Formally defines the syntax of the content of the HTML style global attribute.
CSS Backgrounds and Borders Module Level 3 Candidate Recommendation

Adds:

The CSS4 iteration of the Backgrounds and Borders specification is already in progress, though it still hasn't reached the First Public Working Draft stage, it plans to add the ability to clip a border (with the CSS border-clip, border-clip-top, border-clip-right, border-clip-bottom, and border-clip-left properties) or to control the shape of the border in a corner (using the CSS border-corner-shape property).

CSS Multi-column Layout Module Candidate Recommendation
Adds support for easy multi-column layouts using the CSS columns, column-count, column-fill, column-gap, column-rule, column-rule-color, column-rule-style, column-rule-width, column-span, column-width, break-after, break-before, and break-inside.
CSS Speech Module Candidate Recommendation
Defines the speech media type, an aural formatting model and numerous properties specific for speech-rendering user agents.
CSS Image Values and Replaced Content Module Level 3 Candidate Recommendation

Defines the <image> data type.

Extends the url() syntax to support image slices using media fragments.

Adds:

  • The dppx unit to the <resolution> data type.
  • The image() function as a more flexible alternative to url() to define an image from an url.
    At risk : due to insufficient browser support, standardization of the image() function may be postponed to the next iteration of this module .
  • Support for linear-gradient(), repeating-linear-gradient(), radial-gradient() and repeating-radial-gradient().
  • The ability to define how a replaced element should fit in its element, using the CSS object-fit property.
    At risk : due to insufficient browser support, standardization of the object-fit and property may be postponed to the next iteration of this module .
  • The ability to override the resolution and orientation of an external image using the CSS image-resolution and image-orientation properties.
    At risk : due to insufficient browser support, standardization of the image-resolution and image-orientation properties may be postponed to the next iteration of this module .

The CSS Image Values and Replaced Content Level 4 which will supersede CSS Image Level 3 is in development and is a Working Draft.

CSS Values and Units Module Level 3 Candidate Recommendation

Makes initial and inherit keywords usable on any CSS property.

Formally defines the CSS data types of CSS 2.1, that were implicitely defined by their grammar token and some textual precisions.

Adds:

  • Definition for new font-relative length units: rem and ch .
  • Definition for viewport-relative length units: vw, vh, vmax, and vmin .
  • Precision about the real size of the absolute length units, which are not really absolute, but defined in relation with the reference pixel .
  • Definition for <angle>, <time>, <frequency>, <resolution>.
  • Normative value to the definition of <color>, <image>, and <position>.
  • Definition for the calc(), attr(), and toggle() functional notations.
    At risk: due to insufficient browser support, standardization of the calc(), attr(), and toggle() functional notations may be postponed to the next iteration of this module.

Several types definition, like <ident> and <custom-ident>, have been deferred to CSS Values and Units Module Level 4.

CSS Flexible Box Layout Module Last Call Working Draft
Add a flexbox layout to the CSS display property and several new CSS properties to control it: flex, flex-align, flex-direction, flex-flow, flex-item-align, flex-line-pack, flex-order, flex-pack, and flex-wrap.
CSS Conditional Rules Module Level 3 Candidate Recommendation
Adds features for conditional processing of parts of style sheets, conditioned on capabilities of the browser or the document the style sheet is being applied to. It consists mainly in allowing nested at-rules inside @media and the adding of a new CSS at-rule, @supports, and a new DOM method CSS.supports().
CSS Text Decoration Level 3 Candidate Recommendation

Extends:

Adds:

Precises:

  • The paint order of the decorations.

At risk: due to insufficient browser support, standardization of the text-decoration-skip, line positioning rules and the ability to place both emphasis marks and ruby above the same base text may be postponed to the next iteration of this module.

CSS Fonts Module Level 3 Candidate Recommendation

Amends the CSS2.1 Font matching algorithm to be closer to what is really implemented.

Adds:

CSS Cascading and Inheritance Level 3 Candidate Recommendation

Adds:

  • The initial, unset values for properties.
  • The CSS all property.
  • The scoping mechanism.

Precises:

  • Interaction of media-dependent @import statements and style sheet loading requirements.
CSS Writing Modes Module Level 3 Candidate Recommendation
Defines the writing modes of both horizontal and vertical scripts and precises how the CSS direction and unicode-bidi properties interact with the new CSS text-orientation property, and extends them where needed.
CSS Shapes Module Level 1 Candidate Recommendation
Defines geometric shapes, which can be applied to floats. These shapes describe areas, around which inline content wraps instead of wrapping around the bounding box.
CSS Masking Level 1 Candidate Recommendation
Defines a way for partially or fully hiding portions of visual elements. It describes how to use another graphical element or image as a luminance or alpha mask.

Modules in the refining phase

Specifications that are deemed to be in the refining phase are already fairly stable. Though changes are still expected, they shouldn't create incompatibilities with current implementations; they should mainly define behavior in edge cases.

Web Animations Working Draft
 
CSS Counter Styles Level 3 Candidate Recommendation
 
Compositing and blending Level 1 Candidate Recommendation
 
CSS Syntax Level 3 Candidate Recommendation
Precises how charsets are determined; minor changes in parsing and tokenization algorithms.
CSS Will Change Module Level 1 Working Draft
 
CSS Transitions Working Draft
Allows the definition of transitions effects between two properties values by adding the CSS transition, transition-delay, transition-duration, transition-property, and transition-timing-function properties.
CSS Animations Working Draft
Allows the definition of animations effects by adding the CSS animation, animation-delay,animation-direction, animation-duration, animation-fill-mode, animation-iteration-count, animation-name, animation-play-state, and animation-timing-function properties, as well as the @keyframes at-rule.
CSS Transforms Level 1 Working Draft

Adds:

  • the support of bi-dimensional transforms to be applied to any element using the CSS transform and transform-origin properties. The supported transforms are: matrix(), translate(), translateX(), translateY(), scale(), scaleX(), scaleY(), rotate(), skewX(), and skewY().
  • the support of tri-dimensional transforms to be applied to any element by adding the CSS transform-style, perspective, perspective-origin, and backface-visibility properties and extended the transform property with the following transforms are: matrix 3d(), translate3d(), translateZ()scale3d(), scaleZ(), rotate3d(), rotateX()rotateY(), rotateZ(), and perspective().

Note: this specification is a merge of CSS 2D-Transforms, CSS 3D-Transforms and SVG transforms.

CSS Fragmentation Module Level 3 Candidate Recommendation
Defines how partitions of a Web page should happen, that is page, column breaks, and widows and orphans handling.

Adds:

  • Support for defining the behavior of decorations, that is borders and background colors or images, when a box is breaked (at a page, column or line-break) with the CSS box-decoration-break property.
CSS Text Level 3 Working Draft

Extends:

  • the CSS text-transform property with the value full-width.
  • the CSS text-align property with the value start, end, start end, and match-parent for a better support of documents with multiple directionalities of text.
  • the CSS text-align property with a <string> value to align on that character. This is useful to align number on the decimal point.
  • the CSS word-spacing and letter-spacing properties with range constraints to control flexibility in justification.

Adds:

A few features present in early CSS Text Level 3 draft have being postponed to the next iteration of this module .

CSS Custom Properties for Cascading Variables Module Level 1 Working Draft
Defines a mechanism allowing to define variables in CSS.
Compositing and blending Level 1 Candidate Recommendation
 

Modules in the revising phase

Modules that are in the revising phase are much less stable than those in the refining phase. Often the syntax is still under scrutiny and may evolve a lot, in a non-compatible way. Alternative syntaxes are tested and often implemented.

CSS Basic User Interface Module Level 3 Candidate Recommendation

Adds:

  • The ability to tweak the box model using the CSS box-sizing property.
    At risk: due to insufficient browser support, standardization of the padding-box value may be postponed to the next iteration of this module .
  • Allow the styling of forms according their content using the CSS :indeterminate, :default, :valid, :invalid, :in-range, :out-of-range, :required, :optional, :read-only, and :read-write pseudo-classes and the ::value, ::choices, ::repeat-item, and ::repeat-index pseudo-elements.
    At risk: due to insufficient browser support, standardization of the pseudo-elements ::value, ::choices, ::repeat-item, and ::repeat-index may be postponed to the next iteration of this module .
  • Support for icons, defined by the CSS icon property simultaneously with the new icon value of the CSS content property.
    At risk: due to insufficient browser support, standardization of the icon property and the icon value may be postponed to CSS4.
  • Support for the CSS outline-offset property giving more control on the position of the outline.
  • Support for the CSS resize property allowing Web authors to control if and how elements should be resized.
  • Support for the CSS text-overflow property defining how text overflows, if needed.
    At risk: due to insufficient browser support, the 2-value syntax of this property as well as the support for <string> values may be postponed to the next iteration of this module .
  • The ability to define the hotspot of a cursor as well as the new none, context-menu, cell, vertical-text, alias, copy, no-drop, not-allowed, nesw-resize, nwse-resize, col-resize, row-resize, all-scroll, zoom-in, zoom-out, extending the cursor property.
  • The ability to specify the sequential navigation order (that is the tabbing order ) using the CSS nav-index, nav-up, nav-right, nav-left, nav-down properties.
    At risk: due to insufficient browser support, standardization of the navigation properties may be postponed to the next iteration of this module .
  • The ability to control the usage of an IME editor, using the CSS ime-mode property.
    At risk: due to insufficient browser support, standardization of the ime-mode property may be postponed to the next iteration of this module .

An early list of what could be in the next iteration of the CSS Basic User Interface Module is available.

CSS Grid Layout Working Draft
Add a grid layout to the CSS display property and several new CSS properties to control it: grid, grid-area, grid-auto-columns, grid-auto-flow, grid-auto-position, grid-auto-rows, grid-column, grid-column-start, grid-column-end, grid-row, grid-row-start, grid-row-end, grid-template, grid-template-areas, grid-template-rows, and grid-template-columns.
CSS Box Alignment Module Working Draft
 
CSS Paged Media Module Level 3 Working Draft
 
CSS Object Model (CSSOM) View Module Working Draft
 
Selectors Level 4 Working Draft
 

Modules in the exploring phase

CSS Image Values and Replaced Content Module Level 4 Working Draft

Extends:

  • the image() functional notation to describe the directionality of the image (rtl or ltr), allowing for bidi-sensitive images.
  • the image-orientation property by adding the keyword from-image, allowing to follow EXIF data stored into images to be considered.

Adds:

  • the image-set() functional notation to allow the definition to equivalent images at different resolution allowing for resolution-negotiated selection of images.
  • the element() functional notation allowing the use of part of the page as image.
  • the cross-fade() functional notation allowing to refer to intermediate images when transitioning between two images and defines the interpolation between two images.
  • the conic-gradient() and repeating-conic-gradient() functional notation describing a new type of gradient.
  • the image-rendering property that allow to define how resize of the object should be handled.
CSS Device Adaptation Working Draft
Adds a new at-rule, @viewport, allowing to specify the size, zoom factor, and orientation of the viewport that is used as the base for the initial containing block.
CSS Generated Content for Paged Media Module Working Draft
Adds the ability to tailor printed version of a document by allowing to control header, footer but also references tables like indexes or tables of content.
CSS Exclusions Module Level 1 Working Draft
Extends the floats mechanism to define exclusion regions in any positioning scheme. Adds the notion of shapes, in which content must flows.
CSS Lists and Counters Module Level 3 Working Draft
Extends the list counter mechanism so that list markers can be styled and Web developers can define new list counter schemes.
CSS Regions Module Level 1 Working Draft
Defines a new mechanism allowing content to flow across, eventually non-contiguous, multiple areas called regions.
CSS Device Adaptation Working Draft
Adds a new at-rule, @viewport, allowing to specify the size, zoom factor, and orientation of the viewport that is used as the base for the initial containing block.
Filter Effects Module Level 1 Working Draft
 
CSS Grid Layout Working Draft
 
CSS Intrinsic & Extrinsic Sizing Module Level 3 Working Draft
 
CSS Line Grid Module Level 1 Working Draft
 
CSS Positioned Layout Module Level 3 Working Draft
 
CSS Ruby Layout Module Level 1 Working Draft
 
CSS Object Model (CSSOM) Working Draft
 
CSS Overflow Module Level 3 Working Draft
 
CSS Font Loading Module Level 3 Working Draft
 
CSS Display Module Level 3 Working Draft
 
CSS Scoping Module Level 1 Working Draft
 
Media Queries Level 4 Working Draft
 
Non-element Selectors Module Level 1 Working Draft
 
Geometry Interfaces Module Level 1 Candidate Recommendation
 
CSS Inline Layout Working Draft
 

Modules in the rewriting phase

Modules that are in the rewriting phase are outdated and require to be rewritten. The syntax is still under scrutiny and may evolve a lot, in a non-compatible way. Alternative syntaxes are tested and often implemented.

CSS Basic Box Model Working Draft
 
CSS Generated Content Module Level 3 Working Draft
 
Unknown Unknown
 

 

Document Tags and Contributors

 Contributors to this page: mrstork, prayash, nguyenmanh1507
 Last updated by: mrstork,