Wikipedia:TemplateStyles

This page is a guideline on the Simple English Wikipedia. Many editors agree with the ideas on this page. It is a good idea to follow it, but it is not policy. You can change the page as needed, but please use the talk page to make sure that other editors agree with any big changes.

' TemplateStyles' allow custom CSS pages to style content without an interface administrator having to edit sitewide CSS. TemplateStyles make it more convenient for editors to style templates. For example, those for which the sitewide CSS for the mobile skin or another skin (e.g., Timeless) currently negatively affects the display of the template.

Despite the name, templateStyles works on all types of pages, not just templates.

• The style must apply only to the associated template's output. It may also apply to highly relevant nearby wikitext where the template is used. (For example, many table templates should have TemplateStyles that are provided entirely in templates or that may provide a legend to a wikitext table.) It would otherwise be confusing if adding a template to one part of a page were to completely or partially change the display or styling of an unrelated part.
• Style pages should be associated with a specific template or group of templates and named accordingly. This allows style pages to be easily identified and edited. In general, this means that a style page should be a subpage of the related template, e.g.: Template:myTemplate/styles.css or Template:myTemplate/styles-foo.css, but not Template:styles-foo.css nor Template:foo.css.
• Generally follow the MediaWiki coding conventions for CSS. Some specifics:
  • Use selectors that are highly likely unique to the template being used. This reduces the chance of conflicting CSS rules arising accidentally. Examples: Use .myTemplate-row rather than .row or .myTemplate tr rather than tr.
  • Avoid using #id per the conventions. HTML IDs are supposed to be unique on a page. Templates are rarely used uniquely, and those that are initially single-use-per-page are often later used in unanticipated ways. Use classes instead of IDs for styling.
  • Avoid using !important per the conventions, except in mobile views to override style input from the associated template. Use of !important in TemplateStyles is exceptionally difficult to override because of the loading order of styles (personal CSS then TemplateStyles).
• In templates intended to be substituted, or those likely to be substituted, use {{ifsubst}} to remove the TemplateStyles tag. Example: {{allcaps}}.
  • Inline styles may be used in a substituted template as the "if substed" case. Example: {{smallcaps}}.
• Images that do not require attribution (i.e., those in the public domain) are the only images that may be used as background images. For normal file usage, attribution is provided on the file description page, accessed by clicking the image. This is not possible if the image is being used as the background.
• The protection level of style pages should match their associated template. If a template is high-risk, its styles are also high-risk and should have the same protection. If a template is not high-risk, then vandalism to cause chaos could be achieved just by editing the template itself. A higher protection level for the style page would encourage editors to add inline styles to the template since the template would be editable, but the style page would not. Any templates using CSS pages with the wrong protection level will be categorized in Category:Templates using TemplateStyles with a different protection level.
• Remember to add /* {{pp-template}} */ to any protected CSS pages to ensure that they display the appropriate lock icon. Protected templates using CSS pages that lack the lock icon will be categorized in Category:Templates using TemplateStyles without padlocks.

Note that the Manual of Style, including the Accessibility guidelines, still applies.

1. In Template:myTemplate, identify all of the inline styles that can be moved to a separate stylesheet.
2. Create Template:myTemplate/styles.css containing all the classes that will replace the inline styles. Use template-specific class names where possible.
3. In Template:myTemplate (or it's Template:myTemplate/sandbox if you want to test first), add <templatestyles src="myTemplate/styles.css" /> (you don't need to specify the Template: namespace). It's probably best at the top so that it is obvious and to avoid a flash of unstyled content, but it will need to be on its own line if the template begins with wiki markup that has to start on a new line (e.g. wiki-table).
4. Amend the template (or sandbox) to replace the inline styles with the classes you defined in Template:myTemplate/styles.css
5. Do as much checking as you can. If you tested in the sandbox, you can check the test cases page where it exists, but specifically check that the styles you affected render properly.
   1. Specifically, for templates meant to be used inline, check to see if there are uses inside of links. TemplateStyles templates will not work inside links (right now).
6. If you used the sandbox, either make an edit request for the main template or do the update if you are confident of your changes.
7. Request or amend the protection level of Template:myTemplate/styles.css to match that of Template:myTemplate as necessary.
8. Add {{Uses TemplateStyles}} to the template's documentation to show which TemplateStyles stylesheets it uses.

• Uses of TemplateStyles stylesheets are recorded just like template transclusion and Scribunto module invocation. Special:WhatLinksHere and the "Templates used in this preview" section beneath the edit form will work for them as usual.
• To search for TemplateStyles stylesheets, you can search for contentmodel:sanitized-css. See also mw:Help:CirrusSearch#Contentmodel.
• When {{Uses TemplateStyles}} is placed on a template's documentation, it adds the template to Category:Templates using TemplateStyles. If the TemplateStyles stylesheet has a lower protection level, the template will be tracked in Category:Templates using TemplateStyles with a different protection level (3 pages).
• TemplateStyles experiments can be created at Template:TemplateStyles sandbox, e.g. for use in Module:Sandbox module experiments.
• TemplateStyles pages can be created outside of the template or module namespaces by either first creating them in template namespace and moving them, or (for admins and template editors) by using Special:ChangeContentModel. Regardless of the method, creating a .css page in userspace can only be done by the user in question or an interface admin, but once it is created, anyone can edit it.
• Moving a sanitized CSS page will not create a redirect.

Because of how TemplateStyles is implemented, overriding TemplateStyles in your personal CSS requires a little more effort than normal. The rules on a specific TemplateStyles sheet are not the full CSS rules, nor can you match the selectors to override them.

1. Each selector is 'hoisted' to .mw-parser-output, so to override a rule in a TemplateStyles sheet that looks like .documentation {}, a naive override in your personal CSS file would need to look like .mw-parser-output .documentation {}.
2. However, in the HTML each TemplateStyles style is always placed after your personal CSS file loads. Accordingly, the new rule would need to be more specific. That can come in a couple of ways. The easiest is to select the HTML element as in: .mw-parser-output div.documentation {}. Another way would be to double one of the class selectors, as in .mw-parser-output.mw-parser-output .documentation {} or .mw-parser-output .documentation.documentation {}. This latter way is a little more future-proof but looks a little weirder.
3. Lastly, !important can always override styles in your personal CSS. The usual caveats regarding !important apply. I prefer one of the two options in bullet two if possible. (You must do this to override inline styles, regardless of the above; some templates cannot move everything to TemplateStyles per the flexibility given to template users. Implementers of templates should consider whether parameters like style and width are necessary. See also phab:T200632.)

• mw:Help:TemplateStyles/examples
  • mw:Template:Stylish (CSS)
  • mw:Template:ResponsiveAmboxExample (CSS)
• Template:Thermometer and Template:Thermometer/styles.css give a simple demonstration of how TemplateStyles may be mixed with inline styles (where a parameter is passed to change one or more styles)

• Wikipedia:Lua

• mw:Extension:TemplateStyles
• mw:Help:TemplateStyles