Typography refresh/vi

Tài liệu này trình bày về một bản cập nhật mới liên quan đến kiểu trình bày của giao diện 'Vector' mặc định trong các dự án Wikimedia và gói phần mềm MediaWiki. Ghi chú: thay đổi này vẫn chưa được áp dụng cho các tập tin gốc của MediaWiki, thời điểm thực hiện vẫn còn ở phía trước (tính đến ngày 2014-03-14).

Tóm tắt các thay đổi
We approached this update to Wikimedia's default typography with the following requirements in mind:

In that context, we've made the following changes:
 * 1) Readability: Typefaces must be legible and beautiful at all sizes. Type as an element must help differentiate the interface (such as site navigation) from article content.
 * 2) Consistency: A consistent visual experience across desktop and mobile devices.
 * 3) Availability: All typefaces we use must be already usable (or made available) on all platforms where Wikimedia projects are present. Any selections must degrade gracefully across devices and platforms (Mac OS X, Windows, Linux, and mobile operating systems).
 * 4) Accessibility: Wikimedia content must be highly accessible to all, including those with impairments.


 * New font specifications: We have set the following font families: heading styles have been set to "Linux Libertine, Georgia, Times, serif". Body copy (the main text of pages) has been set to "Arimo, Liberation Sans, Helvetica Neue, Helvetica, Arial, sans-serif".


 * Note that these lists do not mean you will receive all of these fonts. Rather, your browser and operating system will look for the first font in the list that you have installed, and will present that.


 * New spacing and sizing for headings, body copy, and leading: With the current text width, headings need to clearly stand out and the leading (whitespace between lines) needs to be sufficient to enable readability without creating eye fatigue. Headings will now be set to the following: H1 (page titles) will be 2em/1.8em, H2 (main section headings) will be 1.6/1.4em. H3 will be 1.4/1.2em, H4 1.2/1em, H5 1/1em. The body copy has been increased to 0.875em (from 0.8em) with 1.6em (from 1.5em) leading to create more airiness. Depending on your browser and operating system, this will translate to slightly different pixel values, but overall results in a slightly larger body font size. The superscript (sup) line-height is now set to 0, to fix a long-standing problem with reference numbers affecting the leading.


 * New body font color: In hex triplets, the body copy color is now set to  on , from   on  . In less technical terms, this means the color has changed from pure black text on a pure white background, to very dark grey text on pure white background. (Colors for links, headings, and other elements have not changed.)


 * Pre-formatted content: Long  content will have a horizontal scrollbar, instead of causing the entire page to become horizontally scrollable.

FAQ
The following are answers to some key questions about this change.

Who will see this change?
All users of Wikimedia sites who use the default Vector skin, including readers and editors. Users who use their preferences or another method to use an alternative skin, like Monobook or Cologne Blue, will see no changes.

Please note that users who have customized their personal CSS, or who are on a site where local administrators have altered site-wide CSS, may notice discrepancies with the new defaults. Please check this summary and FAQ to see if a particular design element should be attributed to this change.

What was the problem with our typography to begin with?
Text is our core visual element of Wikimedia projects, whether it's an encyclopedia (like Wikipedia) or a smaller project like Wikisource and Wikibooks. We want our users to sense accuracy, reliability, and clarity from our design, just like the actual content they are reading. Prior to this typography update, we had more than 20 arbitrarily defined type sizes on desktop alone, which appeared inconsistent for our users. The type size was too small for many readers, and the line height could make reading long form content difficult. For headings, these should act as entry points in a long pages of text and were styled accordingly to aid readability. We sought to achieve better balance and cohesiveness for users to efficiently scan the page or engage in long form reading.

The functional problems with our older styles were first addressed via improvements to our mobile typography. That gave us a chance to test a larger type size, increased leading, and serif headings. Now, it is time to address readability and accessibility in all languages/projects, as well as create consistency in the design language across desktop, mobile web, and apps.

Is there a perfect font that meets our readability needs in all scripts? Do we think this is it?
No, there is no one perfect font which embodies... We have to make a practical decision based on what comes close to meeting all these requirements, within our constraints. Millions of users read Wikipedia on different devices every day. The current font selections will bring improved readability and consistency across platforms, even if they're not perfect.
 * 1) Ubiquity: i.e availability on all popular desktop and mobile operating systems.
 * 2) Proper rendering of glyphs and diacritics: for hundreds of non-Latin scripts, as well as good kerning for character pairs, so users do not have to squint to read characters.
 * 3) Respectable x-height: so type is legible at small sizes for things like left navigation, captions, terms of service or secondary information.
 * 4) Hinting: avoiding blurriness of characters at small sizes, particularly on Windows.

Why is the type size and leading increased?
This is a small, conservative change. The previous type size was unreadable to many users. We found through user feedback that text zooming was used extensively to make the text more readable for those with even basic vision issues or impairments, since we endeavor to make the information accessible to all users, this change felt like a basic requirement for any improvement in this area. Along with the type size the leading has also been increased to 21px leading, following typographic standards for leading i.e 120% of the type size. This helps readers who go past the introduction and read long paragraphs.

The body copy is the focus of pages on Wikimedia projects. For most language projects the text size is small and dense with our current measure. The lack of airiness lends some efficiency but creates eye fatigue with extended reading. Also, under 14px is not recommended for non-Latin scripts. Words carry superscripts and glyphs which tend to get squashed and cannot be deciphered without squinting.

Why are we using serif fonts for the headings?
For better contrast and distinction between body and headings. Headings act as entry points when users are scanning a page. Headings add some visual diversity to our font stack. Both headings and images play the important role of breaking up the monotony of the page. Combining serif and sans-serif is not an unusual or original idea.

Why did we specify Linux Libertine, Georgia, and Times as the serif fonts?
Section titles are entry points into the article. A serif font provides visual differentiation and character compared to the body copy, which helps a user scan the page. Serif are also well-known for conveying a traditional demeanor that is in keeping with our design goals.

Linux Libertine is not widely available, but is a well-designed and free/open serif font that is also used in the Wikipedia logo. This makes it a ubiquitous part of the Wikimedia design language, as well as being appropriate for use in headings. Georgia is a font optimized for browsers and screens. It is also widely available on our most popular platforms, including for users of Windows, Mac OSX, and iOS. Linux Libertine and Georgia acts as good complementary fonts, and pair well with Helvetica and Arial. Times is set specifically to ensure that users on Linux systems have a good serif by default – Linux systems do not by default include Linux Libertine, nor Georgia. By setting Times, most Linux users will see Nimbus Roman No9 L.

Why did we specify new sans-serif fonts?
The previous state of our body content is that only "sans-serif" was specified, leaving it up to the browser to use its default sans-serif. With the exception of Helvetica, the fonts that most browsers use in this condition do not account for proper rendering of glyphs, pairs, and diacritical marks at small sizes. There is no free/open font that addresses this need and is ubiquitously available (see table).

Of all the free/open options, the closely-related fonts of Liberation Sans and Arimo had the best display characteristics (strong x-height and works well for readability at all sizes). The letterforms closely resemble Helvetica and Arial so it provides for a consistent experience. Arimo had the best technical compliance (accurate rendering of obscure Unicode features), but is only installed by default in ChromeOS. Liberation Sans has a respectable amount of ubiquity and it is produced by Red Hat who can help us with addressing rendering issues. We specified Neue Helvetica for Mac users, as it is a slightly more developed version of Helvetica where punctuation has been improved, the x-height is slightly more consistent, and in some cases it has more rounded bowls and counters. Overall it is an optimization of Helvetica, though it may not be as ideal in all scripts.

We specify fonts both to achieve consistency across devices and platforms and to guarantee appropriate readability and rendering at small sizes for Latin and non-Latin scripts alike. With the specifications in place, users who are interested can download the free/open fonts that have been tested or report issues to us for the fallback cases, which will allow us to address issues in a more systematic manner.

Why did we include non-free fonts in the font stack?
The stack specified a range of fonts from Helvetica Neue to Arial that are available across all major platforms. Even though Arial is widely used as a default, we need to specify it so there the CSS degradation is predictable. To ensure a reliable experience to users across platforms as best as we can, we decided to include non-free fonts in the stack since many operating systems (such as Windows, MacOS, and iOS) do not have any FOSS fonts installed by default.

It is particularly important to note that, because of the way CSS font-family settings work, specifying a particular font does not create a hard dependency on that font, nor does it cause the user to download that font. This means that fonts we specify only appear if the user has them already, and Wikimedia text will continue to appear regardless of whether you have a particular font or not.

What about using webfonts?
Webfonts is a system to deliver a font to users who do not have it installed. This involves having a user's browser download a font we provide, which causes additional resources to load and would have a negative impact on site performance (i.e. how fast pages load). This is particularly true for older browsers. In the future we may explore using webfonts, but for now this update provides greater readability and consistency while not degrading page load times.

Why did we change the body text color?
The new values ( on  ) have a contrast ratio of 15.3:1, which is a AAA rating according to WCAG 2.0 1.4.6. Pure black for both body copy and captions is not recommended against white for several reasons. Dyslexic users are sensitive to the juxtaposition of pure black text on a pure white background due to its high contrast. This can cause the words to swirl or blur together. To avoid this, use a slightly off-white color for your background, like a light gray, or decrease the contrast between foreground (text) and background. For users without accessibility issues, the harsh contrast of pure black on pure white can increase eye strain as well.

How did this change happen?
This typography update was first tested for four months, and then released on mobile web for all Wikimedia projects in October 2012. These included font stack declarations for serif headings and sans serif body copy, as well as increased type size and leading for body copy and captions.

These changes were later brought into desktop as a beta feature, starting in November 2013. This beta feature then went through three major iterations based on community feedback.

How did we get feedback?
Many of the typography changes were first tested on mobile in October 2012, much of the learning was integrated into the typography beta feature for desktop which was launched October 2013 and went through three major releases. During the time the beta feaure was used by over 14,000 users across the top 10 Wikipedias, and more than 100 discussion threads were created on the feature's Talk page.

Can I opt out of changes to the default fonts?
Yes. It is possible for logged-in users of Wikimedia sites to customize their personal CSS (i.e. Special:MyPage/common.css or Special:MyPage/vector.css on each wiki) to override some or all of the changes. You can also define the default font your browser uses to display “serif” and “sans-serif” fonts, if your system does not have any of these specified fonts this browser preference will be used instead.

Did we test this on a variety of browsers and operating systems?
Yes. The new font stack was tested on the following operating systems: Windows XP, Windows 7, and Windows 8, Ubuntu Linux, Mac OSX 10.8, iOS 6 and 7, Android, and Chrome OS. Size, leading, glyphs, hinting and font renders were tested on Windows, Ubuntu Linux, Mac OS 10.8, Android, and ChromeOS.

How will non-English language projects adapt to these changes?
By default, the typography update will be applied to all projects (as part of the Vector skin). There may be languages that need to override some of these styles to accommodate particular scripts. For example, some scripts may need a taller line height or larger font size. Each wiki can override these particular styles by editing their MediaWiki:Vector.css page. We encourage other projects to audit the changes introduced by the update, and override the CSS only where necessary based on their script.

Also see the issues that we are already aware of regarding other language projects.

What about non-Latin scripts?
The old type size in non-Latin scripts was 0.8em (12.8 px). This squashes glyphs and superscripts significantly along with the type being too small to read. Scripts examined were Urdu, Marathi, Bahasa Melayu, Chinese, Korean, Navajo. The body copy type size increase will improve readability for most scripts. Specifically for Navajo, an override will be provided because character pairs render strangely in Helvetica.

Inline CSS guidance can be provided to ensure that languages make overrides on a case-by-case basis as needed. Please comment on the Talk page if you primarily use a non-Latin script and encounter significant problems.

Code links

 * Old/Current:
 * (mediawiki/core.git) / skins / vector / variables.less
 * (mediawiki/core.git) / skins / vector / components / common.less
 * Plus local wiki files such as en:MediaWiki:Vector.css and en:MediaWiki:Common.css


 * New/Typography refresh:
 * (mediawiki/extensions/VectorBeta.git) / less / variables-beta.less
 * (mediawiki/extensions/VectorBeta.git) / less / screen-beta.less
 * (mediawiki/extensions/VectorBeta.git) / less / styles.less
 * Plus local wiki files, as above.


 * (Note: Per the talkpage comment, the ToC/Blockquote/Thumbnail/ext-link-icon elements are being removed in the next few days, so ignore them.)