Альтернативні таблиці стилів
Specifying alternative style sheets in a web page provides a way for users to see multiple versions of a page, based on their needs or preferences.
Firefox lets the user select the stylesheet using the View > Page Style submenu, Internet Explorer also supports this feature (beginning with IE 8), also accessed from View > Page Style (at least as of IE 11), but Chrome requires an extension to use the feature (as of version 48). The web page can also provide its own user interface to let the user switch styles.
The alternate stylesheets are commonly specified using a
<link> element with
rel="stylesheet alternate" and
title="..." attributes, for example:
<link href="reset.css" rel="stylesheet" type="text/css"> <link href="default.css" rel="stylesheet" type="text/css" title="Default Style"> <link href="fancy.css" rel="alternate stylesheet" type="text/css" title="Fancy"> <link href="basic.css" rel="alternate stylesheet" type="text/css" title="Basic">
In this example, the styles "Default Style", "Fancy", and "Basic" will be listed in the Page Style submenu, with the Default Style pre-selected. When the user selects a different style, the page will immediately be re-rendered using that style sheet.
No matter what style is selected, the rules from the reset.css stylesheet will always be applied.
Click here for a working example you can try out.
Any stylesheet in a document falls into one of the following categories:
- Persistent (no
title=""): always applies to the document.
- Preferred (no
title="..."specified): applied by default, but disabled (en-US) if an alternate stylesheet is selected. There can only be one preferred stylesheet, so providing stylesheets with different title attributes will cause some of them to be ignored. See Correctly Using Titles With External Stylesheets for a more detailed discussion.
- Alternate (
title="..."must be specified): disabled by default, can be selected.
When style sheets are referenced with a
title attribute on the <link rel="stylesheet"> or
<style> element, the title becomes one of the choices offered to the user. Style sheets linked with the same
title are part of the same choice. Style sheets linked without a
title attribute are always applied.
rel="stylesheet" to link to the default style, and
rel="alternate stylesheet" to link to alternative style sheets. This tells the browser which style sheet title should be selected by default, and makes that default selection apply in browsers that do not support alternate style sheets.
|CSS Object Model (CSSOM)
The definition of 'CSS Style Sheet Collections' in that specification.
|Working Draft||The CSS OM specification defines the concepts of the style sheet set name, its disabled flag, and the preferred CSS style sheet set name.
It defines how these are determined, and lets the HTML specification define the HTML-specific behaviors by requiring it to define when to create a CSS style sheet.
HTML Living Standard
|Living Standard||The HTML specification defines when and how the create a CSS style sheet algorithm is invoked while handling <link> and <style> elements, and also defines the behavior of
|HTML 4.01 Specification
The definition of 'Alternative style sheets' in that specification.
|Recommendation||Earlier, the HTML specification itself defined the concept of preferred and alternate stylesheets.|