Cascading Style Sheets ( CSS ) is a style sheet language used to describe the presentation of documents written in markup languages ​​like HTML. CSS is the foundation technology of the World Wide Web, alongside HTML and JavaScript.
CSS is designed to allow for the separation of presentations and content, including layout, colors, and fonts. This separation can improve the accessibility of the content, provide more flexibility and control in the presentation characteristic specification, allow multiple web pages to share formats by specifying relevant CSS in separate.css files, and reduce complexity and repetition in structural content.
The separation of formats and content also makes it feasible to present the same markup pages in different styles for different rendering methods, such as on screen, in print, by voice (via speech-based browser or screen reader), and on Braille-based tactile devices. CSS also has rules for alternative formatting if content is accessed on a mobile device.
The name cascading is derived from the specified priority schema to specify the style rule that applies if more than one rule matches a particular element. This tiered priority scheme can be predicted.
The CSS specifications are managed by the World Wide Web Consortium (W3C). The type of Internet media (type MIME) text/css is registered for use with CSS by RFC 2318 (March 1998). W3C operates a free CSS validation service for CSS documents.
In addition to HTML, other markup languages ​​support the use of CSS, including XHTML, plain XML, SVG, and XUL.
Video Cascading Style Sheets
Syntax
CSS has a simple syntax and uses a number of English keywords to specify the names of various style properties.
Style sheet consists of a list of rules . Each rule or set of rules consists of one or more voters , and blocks declarations .
Selector
In CSS, selector declares which part of the markup applies to the style by matching the tags and attributes in the markup itself.
The voters may apply to:
- all elements of a particular type, e.g. second level header h2 The
- element is defined by the attribute, specifically:
- id : unique identifier in document
- class : identifier that can annotate some elements in the document
- elements depend on how they are placed relative to others in the document tree.
Classes and IDs are case-sensitive, starting with letters, and can include alphanumeric characters and underscores. Classes may apply to any number of elements of any element. ID can only be applied to one element.
Pseudo-class is used in the CSS selector to allow formatting based on information not contained in the document tree. One of the most commonly used pseudo-class examples is
: hover , which identifies content only when the user "points to" the visible element, usually by holding the mouse cursor over it. This is added to the selector as in
: a : hover or
element span> : hover . The pseudo class classifies the document elements, such as : visited , whereas pseudo -element create a selection that may consist of a partial element, such as :: first letter .Voters can be combined in many ways to achieve high specificity and flexibility. Multiple selectors can join a space bar to specify elements based on location, element type, id, class, or any combination thereof. The order of voters is very important. For example, div . myClass { color : red ;} applies to all myClass class elements residing in div element, while . myClass color : red ;} applies to all div elements present in myClass class element.
The following table provides a summary of the voter syntax that shows the usage and version of CSS that introduced it.
Block declaration
The declaration block consists of a list of declarations in braces. Each declaration itself consists of property , a colon (: ), and a value . If there are multiple declarations in a block, the semicolon (; ) must be inserted to separate each declaration.
The property is specified in the CSS standard. Each property has a set of possible values. Some properties may affect all types of elements, and others only apply to certain groups of elements.
Values ​​can be keywords, such as "middle" or "inherit", or numerical values, such as 200px (200px), 50vw (50 percent of viewport width) or 80% (80 percent of window width). Color values ​​can be specified with keywords (eg "red"), hexadecimal values ​​(eg # FF0000, also abbreviated # # F00), RGB values ​​on a scale of 0 to 255 (eg rgb ( 255 , 0 , 0 ) ), RGBA values ​​that define color transparency and alpha (eg rgba ( 255 , 0 , 0 , 0 . 8 ) ), or HSL or HSLA value (eg hsl ( 000 , 100 %, 50 %) , ).
Use
Before CSS, almost all attributes of HTML document presentations are present in HTML markup. All font colors, background styles, element alignments, limits and sizes must be explicitly explained, often repeatedly, in HTML. CSS allows authors to move a lot of information to other files, style sheets, resulting in much simpler HTML.
For example, the title (element h1 ), sub-headings ( h2 ), sub-headings ( h3 ), etc., are defined structurally using HTML. On print and on screen, the choice of font, size, color and emphasis for these elements is presentations .
Prior to CSS, the document authors wanted to establish such typography characteristics for, say, all the h2 titles should repeat the HTML's presentational markup for each occurrence of that type of header. This makes the document more complex, larger, and more error-prone and difficult to maintain. CSS allows the separation of presentation from the structure. CSS can specify color, font, text alignment, size, borders, spacing, layout and many other typographic characteristics, and can do it independently for on-screen display and printing. CSS also defines non-visual styles, such as reading speed and emphasis for aural text readers. The W3C has now discontinued the use of all presentational HTML markups.
For example, under pre-CSS HTML, a heading element defined with red text would be written as:
Using CSS, the same element can be encoded using the style property, not the HTML presentation attribute:
The advantage of this may not be immediately obvious (because the second form is actually more verbose), but the power of CSS becomes more apparent when the style property is placed in an internal style element or, even better, an external CSS file. For example, suppose the document contains a style element:
All h1 elements in the document will automatically become red without requiring explicit code. If the author then wants to make the h1 element instead, this can be done by changing the style element to:
rather than painstakingly through the document and change the color for each h1 element.
Styles can also be placed in external CSS files, as described below, and loaded using a syntax similar to:
This further separates the styling of the HTML document, and allows to repeat multiple documents by simply editing the shared external CSS file.
Source
CSS information can be provided from various sources. These sources can be web browsers, users and authors. Information from authors can be further classified into inline, media type, importance, voter specification, sequence of rules, inheritance and property definition. CSS style information can be in a separate document or can be inserted into an HTML document. Some style sheets can be imported. Different styles can be applied depending on the output device used; for example, the screen version can be very different from the print version, so the author can customize the presentation appropriately for each medium.
Style sheets with the highest priority control the content display. Unassigned declarations in the highest priority source are forwarded to a lower priority source, such as the user-agent style. This process is called cascading .
One of the goals of CSS is to enable users to better control the presentation. Someone who finds a hard-to-read oblique headline can apply different style sheets. Depending on the browser and website, users can choose from various style sheets provided by the designers, or can delete all added styles and view the site using the browser's default style, or may override only red-colored styles without changing attributes.
Specificity
Specificity refers to the relative weights of the various rules. This specifies the style that applies to elements when more than one rule is applicable. Based on the specifications, a simple selector (eg H1) has a specificity of 1, the class selector has a specificity of 1.0, and a 1.0.0 specificity selector. Because the specificity value is not carried in the decimal system, commas are used to separate "digits" (CSS rules that have 11 elements and 11 classes will have a specificity of 11.11 instead of 121).
Thus the following rule selector produces the specifics indicated:
Example
Consider this HTML fragment:
In the above example, the declarations in the style attribute override those in the & lt; style & gt; because it has a higher specificity, and thus, the paragraph looks green.
Inheritance
Inheritance is a key feature in CSS; it depends on the ancestral-hereditary relationship to operate. Inheritance is the mechanism by which property is applied not only to certain elements, but also to its derivatives. Inheritance depends on the document tree, which is the hierarchy of XHTML elements in the page based on nesting. The Descendant element can inherit the CSS property value of the attached ancestral element. Generally, the inheritance element inherits the property associated with the text, but the properties associated with the box are not inherited. The inheritable properties are color, font, letter-space, line-height, list-style, text-align, text-indent, text-transform, visibility, whitespace and word-space. Non-inheritable properties are background, delimiter, display, float and clear, height, and width, margin, min- and max-height and -width, outline, overflow, padding, position, text-decoration, vertical-align and z -index.
Inheritance can be used to avoid declaring certain properties over and over in style sheets, allowing for shorter CSS.
Inheritance in CSS is not the same as inheritance in a class-based programming language, where it is possible to define class B as "like class A, but with modification". With CSS, it is possible to style element with "class A but with modifications". However, it is not possible to define such a CSS class B, which can then be used to force some elements without having to repeat modifications.
Example
Given the following style sheets:
Suppose there is a h1 element with elements that emphasize (em) inside:
If no color is assigned to the em element, the word emphasized "describes" inherits the color of the parent element, h1. Style sheet h1 has a pink color, hence, em element is also pink.
Whitespace
Spacing between property and selector is ignored. The snippet of this code:
functionally equivalent to this one:
One common way to format CSS for readability is to identify each property and give it a separate row. In addition to formatting CSS for easy reading, you can use abbreviated properties to write faster code that also processed faster when rendered, such as:
Positioning
CSSÃ, 2.1 defines three positioning schemes:
- Normal flow The
- Inline items are arranged in the same way as the letters in words in the text, one at a time across from the available space until there is no more space, then start a new line below. Block stacks items vertically, like paragraphs and likes items in a bulleted list. The normal stream also includes the relative placement of blocks or inline items, and a run-in box.
- Float
- The floating item is taken out of the normal stream and shifts left or right as far as possible in the available space. Other content then flows alongside floating items.
- Absolute determination
- A completely positioned item has no place on, and has no effect on, the normal flow of other items. It occupies the position specified in its container independently of other items.
Property position
There are four possible values ​​of the position property. If the item is positioned in any way other than static , then the next property top , under , left , and right is used to determine the offset and position.
- Static
- Default values ​​place items in normal stream
- Relative
- Items are placed in normal stream , then shifted or offset from that position. The next stream item is styled as if the item has not been moved.
- Absolute
- Define absolute position . Elements are positioned in conjunction with their nearest non-static ancestors.
- Stay
- This item is fully positioned in a fixed position on the screen even while other documents are scrolled
Float and delete
The float property may have one of three values. Really positioned or fixed the item can not be floated. Other elements usually flow around floating items, unless they are prevented from doing so by the clear property.
- left
- Items float to the left of the line that will appear; other items can flow around the right side.
- right
- Items float to the right of the line that will appear in; other items can flow around the left side.
- clear
- Forcing elements to appear below ('clear') floating element to the left (
clear : span> left ), right ( : right) or both sides (clear : both).
Maps Cascading Style Sheets
History
CSS was first proposed by HÃÆ'  ¥ kon Wium Lie on October 10, 1994. At that time, Lie worked with Tim Berners-Lee at CERN. Several other languages ​​style sheets for the web were proposed around the same time, and discussions on the public mailing list and within the World Wide Web Consortium produced the first W3C CSS Recommendation (CSS1) released in 1996. In particular, Bert Bos's proposal was influential; he became co-author of CSS1 and is considered a co-creator of CSS.
Style sheets have existed in one form or another since the beginning of the Standard Generalized Markup Language (SGML) in the 1980s, and CSS was developed to provide style sheets for the web. One requirement for web style style sheets is for style sheets coming from different sources on the web. Therefore, existing style sheet languages ​​such as DSSSL and FOSI do not match. CSS, on the other hand, lets the style of the document be influenced by several style sheets with a "cascading" style.
As HTML grows, it comes to encompass a wider range of style capabilities to meet the demands of web developers. This evolution gives the designer more control over the look of the site, with more complex HTML costs. Variations in web browser implementations, such as ViolaWWW and WorldWideWeb, make consistent website views difficult, and users have little control over how web content is displayed. The browser/editor developed by Tim Berners-Lee has a hard-coded style sheet into the program. Therefore, style sheets can not be associated with documents on the web. Robert Cailliau, also of CERN, wants to separate the structure from the presentation so that different style sheets can describe different presentations for printing, screen-based presentations, and editors.
Improving web presentation skills is a topic of interest to many people in the web community and nine different styles of sheet styles are proposed on the www-style mailing list. Of these nine proposals, two are very influential on what becomes CSS: Cascading Style Style HTML and Stream Style Style Sheet Proposals (SSP). Two browsers are presented as testbeds for the original proposal; Lie works with Yves Lafon to apply CSS in Arena browser Dave Raggett. Bert Bos applies his own SSP proposal in the Argo browser. After that, Lie and Bos work together to develop the CSS standard ('H' is removed from the name because the style sheet is also applicable to other markup languages ​​besides HTML).
Lie's proposal was presented at the "Mosaic and the Web" conference (then called WWW2) in Chicago, Illinois in 1994, and again with Bert Bos in 1995. Around this time the W3C has been established, and has an interest in development. CSS. It organized a workshop to the end led by Steven Pemberton. This resulted in W3C adding work to the CSS to the submission of an editorial board HTML (ERB). Lie and Bos are the main technical staff on this aspect of the project, with additional members, including Thomas Reardon from Microsoft, participating as well. In August 1996 Netscape Communication Corporation presented an alternative style sheet language called JavaScript Style Sheets (JSSS). The specification is never completed and is no longer valid. At the end of 1996, CSS was ready to become official, and CSS Level 1 Recommendations were published in December.
The development of HTML, CSS, and DOM has all happened in one group, the HTML Editorial Review Board (ERB). Early in 1997, ERB was divided into three working groups: the HTML Working Group, led by Dan Connolly of the W3C; The DOM Working Group, headed by Lauren Wood from SoftQuad; and CSS Working Group, headed by Chris Lilley from the W3C.
The CSS Working Group began addressing unresolved issues with CSS level 1, resulting in the creation of CSS level 2 on November 4, 1997. It was published as a W3C Recommendation on May 12, 1998. CSS level 3, beginning in 1998, is still under development in 2014.
In 2005, the CSS Working Group decided to enforce more stringent standards requirements. This means that published standards such as CSS 2.1, CSS, 3 Selectors and CSS 3 Text are withdrawn from the Proposed Candidate to the Level of Work Draft.
Difficulty with adoption
The CSSà © specifications, 1 completed in 1996. Microsoft Internet Explorer 3 was released that year, featuring some limited support for CSS. IE 4 and Netscape 4.x add more support, but are usually incomplete and have many bugs that prevent CSS from being used effectively. That's more than three years before the web browser reaches the full implementation of the specification. Internet Explorer 5.0 for Macintosh, shipped in March 2000, was the first browser to have CSSÃ, 1 support (more than 99 percent), beyond Opera, which has been a leader since the introduction of CSS support 15 months earlier. Other browsers soon follow after, and many of them also implement CSS 2 parts.
However, even when later 'version 5' web browsers started offering a fairly full CSS implementation, they are still wrong in certain areas and full of inconsistencies, bugs and other habits. Microsoft Internet Explorer 5.x for Windows, as opposed to a very different IE for Macintosh, has the wrong implementation of the 'CSS box model', compared to CSS standards. It is a set of rules that define certain aspects of the size and layout of web page components. This inconsistency and variation of feature support makes it hard for designers to achieve a consistent look across browsers and platforms without the use of solutions called hacks and CSS filters. The IE/Windows box model bug is so serious that when Internet Explorer 6 is released, Microsoft introduces a supplemental 'alternative quirks' interpretation mode, the 'default mode' is corrected. Other non-Microsoft browsers also provide this same 'mode'-switching behavior capability. Unfortunately, since the release of IE 6 in 2001, it has become important for authors of html file webpages to ensure that html contains specific 'standard-compliant CSS intended' markers to show that authors intend CSS to be interpreted correctly, according to standards, with which is meant for IE5/Windows browsers that are outdated. Without this bookmark, web browsers that have quirks mode-switching capabilities will measure objects in web pages like IE5/Windows rather than follow CSS standards.
The problem with the adoption of CSS browser patches, along with errata in the original specification, leads the W3C to revise the CSS 2 standard into CSS 2.1, which moves closer to the current CSS support work snapshot in the HTML browser. Some of the CSS 2 properties that are not successfully executed by the browser are dropped, and in some cases, the specified behavior is changed to bring the standard into line with the existing dominant implementation. CSS 2.1 became Candidate Recommendation on February 25, 2004, but CSS 2.1 was withdrawn to the status of Working Plan on June 13, 2005, and only returned to Candidate Recommendation status on July 19, 2007.
In addition to this problem, the .css extension is used by the software product used to convert PowerPoint files into Compact Slide Show files, so some web servers serve all .css as mime type < code> application/x-pointplus instead of text/css .
Variations
CSS has various levels and profiles. Each level of CSS is built on the latter, usually adding new features and usually symbolized as CSS 1, CSS 2, CSS 3, and CSS 4. Profiles are usually part of one or more CSS levels built for a particular device or user interface. There are currently profiles for mobile devices, printers, and television sets. Profiles should not be confused with media types, added in CSS 2.
CSS 1
The first CSS specification to be the official W3C Recommendation is CSS level 1, published on December 17, 1996. HÃÆ'  ¥ kon Wium Lie and Bert Bos are credited as original developers. Among his abilities is support for
- Font properties like font and emphasis
- Text color, background, and other elements
- Text attributes like the distance between words, letters, and lines of text
- Align text, images, tables, and other elements
- Margin, border, padding, and positioning for most elements
- Unique identification and general classification of attribute groups
The W3C no longer maintains the CSS Recommendation 1.
CSS 2
The CSS level 2 specification was developed by the W3C and published as a recommendation in May 1998. A superset of CSS 1, CSS 2 includes a number of new capabilities such as absolute, relative, and fixed positions of elements and z-index, media type concepts, aural (later replaced by CSS 3 speech modules) and two-way text, and new font properties like shadows.
The W3C no longer maintains CSS 2 recommendations.
CSS 2.1
CSS level 2 revision 1, commonly referred to as "CSS 2.1", fixes errors in CSS 2, removes features that are not well supported or not fully operated and adds browser extensions already applied to specifications. To comply with the W3C Process for standardizing technical specifications, CSS 2.1 goes back and forth between the status of the Work Plan and the Candidate Recommendation status over the years. CSS 2.1 first became the Candidate Recommendation on 25 February 2004, but it was returned to the Working Plan on 13 June 2005 for further review. It returned to the Recommendation Candidate on July 19, 2007 and then renewed twice in 2009. However, due to changes and clarifications made, it again returned to the Last Call Working Draft on December 7, 2010.
CSS 2.1 went to the Recommendation Proposal on 12 April 2011. Upon review by the W3C Advisory Committee, it was finally published as a W3C Recommendation on 7 June 2011.
CSS 2.1 is planned as the first and last revision of level 2 - but low priority work on CSS 2.2 begins in 2015.
CSS 3
Unlike CSS 2, which is a single large specification that defines various features, CSS 3 is split into several separate documents called "modules". Each module adds new capabilities or extends the features defined in CSS 2, maintaining backward compatibility. Work on CSS level 3 begins around the time of publication of the original CSS 2 recommendations. The earliest CSS, 3, was published in June 1999.
Due to modularization, different modules have different stability and status. As of June 2012, there are over fifty CSS modules published from the CSS Working Group, and four of them have been published as official recommendations:
- 2012-06-19: Media Inquiries
- 2011-09-29: Namespaces
- 2011-09-29: Level 3 Launcher
- 2011-06-07: Colors
Some modules have Candidate Recommendations ( CR ) status and are considered quite stable. At the CR stage, implementation is recommended for dropping vendor prefix.
CSS 4
None of the CSS4 specifications are integrated, as they are split into separate "level 4" modules.
Because CSS3 divides the definition of CSS language into modules, modules have been allowed to level up independently. Most modules are level 3 - they build things from CSS 2.1. There are some level-4 modules (such as Image Values, Background & Border, or Voters), which build the functionality of the previous 3-level module. Other modules that define entirely new functions, such as Flexbox, have been designated as "level 1".
The CSS Working Group sometimes publishes "Photographs", a collection of all modules and parts of other designs that are considered stable, can be implemented interoperatively and are therefore ready for use. So far, four best practice documents are now issued as Notes, in 2007, 2010, 2015 and 2017.
Browser support
Every web browser uses a layout engine to render web pages, and support for CSS functionality is inconsistent between them. Because the browser does not parse CSS perfectly, many coding techniques have been developed to target specific browsers with workarounds (commonly known as CSS hacks or CSS filters). The adoption of new functionality in CSS can be hindered by a lack of support in major browsers. For example, Internet Explorer is slow to add support for many features of CSS 3, which slows down the use of these features and damages the reputation of the browser among developers. To ensure a consistent experience for their users, web developers often test their sites across multiple operating systems, browsers, and browser versions, increasing development time and complexity. Tools like BrowserStack have been built to reduce the complexity of maintaining this environment.
In addition to this testing tool, many sites store browser support lists for certain CSS properties, including CanIUse and the Mozilla Developer Network. In addition, CSS 3 defines a feature query, which provides a @supports directive that will allow developers to target browsers with support for certain functions directly within their CSS. CSS that is not supported by older browsers can sometimes be patched using polyfill Javascript, which is part of a Javascript code designed to make the browser behave consistently. This solution - and the need to support fallback functionality - can add complexity to development projects, and as a result, companies often specify a list of browser versions that they will and will not support.
Because websites adopt newer code standards incompatible with older browsers, this browser may be disconnected from accessing many resources on the web (sometimes on purpose). Many of the most popular sites on the internet are not only visually degraded in older browsers because of poor CSS support, but they do not work at all, largely due to the evolution of Javascript and other web technologies.
Limitations
Some limitations of current CSS capabilities include:
- Voters can not go up
- CSS currently does not offer a way to select the parent or the ancestor of elements that meet certain criteria. The CSS Level 4 selector, which is still in the status of the Work Plan, proposes such a selector, but only as part of the "complete" voter profile instead of the "fast" profile used in dynamic CSS styles. More advanced selector schemes (such as XPath) will allow more sophisticated style sheets. The main reason for the CSS Working Group that previously rejected the proposal for parental voters was related to browser performance and additional rendering issues.
- Can not explicitly declare new scope independently of position
- Assign rules for properties such as z-index search for the closest parent element to position: absolute or position: relative attribute. This odd copel has an undesirable effect. For example, it is impossible to avoid declaring a new scope when one is forced to adjust the position of an element, preventing one from using the scope of the desired parent element.
- Pseudo-class dynamic behavior can not be controlled
- CSS implements a pseudo-class that allows user feedback levels by conditional applications of alternative styles. One CSS pseudo-class, "
- Can not mention rule
- There is no way to name the CSS rules, which will allow (for example) client-side scripts to refer to rules even if the selector changes.
- Can not include style from rule to rule
- CSS styles often have to be duplicated in some rules to achieve the desired effect, leading to additional maintenance and require more thorough testing. Some new CSS features are proposed to complete this, but (as of February 2016) have not been applied anywhere.
- Can not target specific text without changing the markup
- In addition to : first letter
Previous issues
In addition, some other issues are present in earlier versions of the CSS standard, but have been lightened:
- Limitations of vertical control
- Although horizontal element placement is always easy to control, vertical placement is often not intuitive, convoluted, or highly unlikely. Simple tasks, such as centering elements vertically or placing a footer no higher than the bottom of the viewing area require complicated and intuitive style rules, or simple but not widely supported rules. The Flexible Box module improves the situation significantly and the vertical control is much easier and is supported in all modern browsers. Old browsers still have the problem, but most of them (especially Internet Explorer 9 and lower) are no longer supported by their vendors.
- No expression
- There is no standard ability to specify property values ​​as simple expressions (like
margin-left: 10% - 3em 4px;). This will be useful in many cases, such as calculating column sizes that are subject to the limit on the sum of all columns. Internet Explorer versions 5 through 7 support the expression statement of proprietary (), with similar functionality. This ownership statement () is no longer supported from Internet Explorer 8 and beyond, except in compatibility mode. This decision was taken for "standard compliance, browser performance, and security reasons". However, a candidate recommendation with a calc () value to overcome this limitation has been published by CSS WG and has since been supported in all modern browsers. - Lack of column declaration
- While it may be in the current CSS 3 (using
column-countmodules), the layout with multiple columns can be complicated to be implemented in CSS 2.1. With CSS 2.1, this process is often done using floating elements, often displayed differently by different browsers, different computer screen shapes, and different display ratios set on a standard monitor. All modern browsers support this CSS 3 feature in one form or another.
Advantages
- Separation of content from presentation
- CSS facilitates the publication of content in various presentation formats based on nominal parameters. Nominal parameters include explicit user preferences, different web browsers, device type used to view content (desktop computer or mobile Internet device), user geographic location and many other variables.
- Consistency of all sites
- When CSS is used effectively, in terms of inheritance and "cascading", global style sheets can be used to influence and style elements throughout the site. If the situation arises that the styling of the element must be changed or adjusted, this change can be done by editing the rules in the global style sheet. Before CSS, this kind of maintenance is more difficult, expensive and time-consuming.
- Bandwidth
- Stylesheets, internal or external, specify a one-time style for various HTML elements selected by
class, type or relationship with others. This is much more efficient than repeating inline style information for each element occurrence. External stylesheets are usually stored in the browser cache, and therefore can be used on many pages without reloading, further reducing data transfer over the network. - page formatting
- With a simple one-line change, different style sheets can be used for the same page. It has the advantage of accessibility, as well as providing the ability to customize pages or sites to different target devices. In addition, the device can not understand the style still displaying the content.
- Accessibility
- Without CSS, web designers should place their pages with techniques such as HTML tables that impede accessibility for users with visual impairments (see tableless Web Design # Accessibility).
Standardization
Framework
The CSS framework is a pre-prepared library intended to make it easier, webpage styles using more standardized cascading Style Sheets language. The CSS framework includes the Foundation, Blueprint, Bootstrap, Cascade Framework, and Materialization. Like programming and scripting language libraries, CSS frameworks are usually included as external sheets. Css referenced in HTML & lt; head & gt; . They provide a number of ready-made options for designing and laying web pages. Although many of these frameworks have been published, some authors use them mostly for rapid prototyping, or to learn from, and prefer to 'craft' the appropriate CSS for each published site without design, maintenance and download overhead as it has many features that not used in site style.
Design methodology
Because the size of the CSS resources used in the project increases, development teams often need to decide on common design methodologies to stay organized. The goal is the ease of development, ease of collaboration during the development and performance of stylesheets implemented in the browser. Popular methodologies include OOCSS - object-oriented CSS, ACSS - atomic CSS, oCSS - Cascade Style Organic Sheet, SMACSS - scalable and modular architecture for CSS and BEM - blocks, elements, modifiers.
References
Further reading
External links
- Official website
- CSS in Curlie (based on DMOZ)
Source of the article : Wikipedia
0 Comments