If you’re using HTML5 elements then you’re probably also using a JavaScript shiv to help make it possible to style those elements in versions of Internet Explorer prior to IE9. But when JavaScript is disabled the accessibility of the content may be affected in these versions of IE. This is one way to provide a more accessible fallback.

The concept is to ensure that all modern browsers are served the default style sheet(s) and that people using older versions of IE only download them if JavaScript is enabled. When JavaScript is not enabled, people using those browsers can be served either no styles at all (as Yahoo! suggests for browsers receiving C-Grade support) or simple fallback styles.

Client-side method: conditional comments

Doing this on the client-side comes at the cost of having to litter your code with proprietary conditional comments. First, it’s necessary to comment out the default style sheet(s) from versions of IE earlier than IE9. All other browsers will be able to read the file(s).

<!--[if ! lt IE 9]><!-->
<link rel="stylesheet" href="/css/default.css">
<!--<![endif]-->

For earlier versions of IE, an HTML5 shiv is included and the necessary link elements are created and added to the DOM using JavaScript. This means that when JavaScript is not enabled in IE7 or IE8 the style sheet will not be present, resulting in an unstyled HTML page. In this example, IE6 won’t be served CSS at all.

<!--[if (IE 7)|(IE 8)]>
<script src="/js/html5.js"></script>
<script>
   (function() {
      var link = document.createElement("link");
      link.rel = "stylesheet";
      link.href = "/css/default.css";
      document.getElementsByTagName("head")[0].appendChild(link);
   }());
</script>
<![endif]-->

To support multiple style sheets, an array and for loop can be used.

<!--[if (IE 7)|(IE 8)]>
<script src="/js/html5.js"></script>
<script>
   (function() {
      var css = [
         '/css/default.css',
         '/css/section.css',
         '/css/custom.css'
      ];
      var i;
      var link = document.createElement('link');
      var head = document.getElementsByTagName('head')[0];
      var tmp;

      link.rel = 'stylesheet';

      for(i = 0; i < css.length; i++){
         tmp = link.cloneNode(true);
         tmp.href = css[i];
         head.appendChild(tmp);
      }
   }());
</script>
<![endif]-->

Thanks to Remy Sharp and Mathias Bynens for helping me to improve this script. Fork it.

Rather than serving unstyled content, it may be preferable to provide some simple fallback styles. This can be done by linking to a separate style sheet wrapped in noscript tags. In this example, IE6 will always use these legacy styles while IE7 and IE8 will do so only when JavaScript is disabled.

<!--[if lt IE 9]>
<noscript>
   <link rel="stylesheet" href="/css/legacy.css">
</noscript>
<![endif]-->

You may wish to use a generic style sheet, such as “Universal IE6 CSS”, or spend a few minutes crafting your own and ensuring that the typography and colours approximate those in the default style sheet.

The complete example code is as follows:

<!--[if ! lt IE 9]><!-->
<link rel="stylesheet" href="/css/default.css">
<!--<![endif]-->

<!--[if (IE 7)|(IE 8)]>
<script src="/js/html5.js"></script>
<script>
   (function() {
      var link = document.createElement("link");
      link.rel = "stylesheet";
      link.href = "/css/default.css";
      document.getElementsByTagName("head")[0].appendChild(link);
   }());
</script>
<![endif]-->

<!--[if lt IE 9]>
<noscript>
   <link rel="stylesheet" href="/css/legacy.css">
</noscript>
<![endif]-->

Server-side method: user-agent string detection

The drawbacks of current client-side approaches to IE fallbacks is that they are IE-specific, make extensive use of conditional comments, and have to use JavaScript to create or rewrite link elements. This blog makes use of an alternative approach: server-side user-agent detection. It was inspired by Yahoo!’s Graded Browser Support strategy – created by Nate Koechley – which recommends that all CSS and JavaScript is withheld from legacy browsers (not limited to IE).

The source code in the head of this blog changes when viewed in modern browsers, IE8, and legacy browsers that are incapable of styling HTML5 elements (e.g. Firefox 2) or lack adequate CSS2.1 support (e.g. IE7).

Browsers are assumed to be capable; there is no need to update the script every time a new browser is released. Only when a browser is deemed to be severely incapable is it added to a “blacklist” and served simple styles to ensure that the accessibility of the content is maintained. This is the method I prefer, although it does require more time upfront.

The git-checkout command can be used to update specific files or directories in your working tree with those from another branch, without merging in the whole branch. This can be useful when working with several feature branches or using GitHub Pages to generate a static project site.

The git-checkout manual page describes how the git checkout command is not just useful for switching between branches.

When <paths> or --patch are given, git checkout does not switch branches. It updates the named paths in the working tree from the index file or from a named <tree-ish> (most often a commit)…The <tree-ish> argument can be used to specify a specific tree-ish (i.e. commit, tag or tree) to update the index for the given paths before updating the working tree.

In git, a tree-ish is a way of referring to a particular commit or tree. This can be a partial sha or the branch, remote, and tag name pointers.

The syntax for using git checkout to update the working tree with files from a tree-ish is as follows:

git checkout [-p|--patch] [<tree-ish>] [--] <pathspec>…

Therefore, to update the working tree with files or directories from another branch, you can use the branch name pointer in the git checkout command.

git checkout <branch_name> -- <paths>

As an example, this is how you could update your gh-pages branch on GitHub (used to generate a static site for your project) to include the latest changes made to a file that is on the master branch.

# On branch master
git checkout gh-pages
git checkout master -- myplugin.js
git commit -m "Update myplugin.js from master"

The need to update my gh-pages branch with specific files from my master branch was how I first found out about the other uses of the checkout command. It’s worth having a read of the rest of the git-checkout manual page and experimenting with the options.

Normalize.css is a small CSS file that provides better cross-browser consistency in the default styling of HTML elements. It’s a modern, HTML5-ready, alternative to the traditional CSS reset.

• Normalize.css project site
• Normalize.css source on GitHub

Normalize.css is currently used in some form by Twitter Bootstrap, HTML5 Boilerplate, GOV.UK, Rdio, CSS Tricks, and many other frameworks, toolkits, and sites.

Overview

Normalize.css is an alternative to CSS resets. The project is the product of 100’s of hours of extensive research by @necolas and @jon_neal on the differences between default browser styles.

The aims of normalize.css are as follows:

• Preserve useful browser defaults rather than erasing them.
• Normalize styles for a wide range of HTML elements.
• Correct bugs and common browser inconsistencies.
• Improve usability with subtle improvements.
• Explain the code using comments and detailed documentation.

It supports a wide range of browsers (including mobile browsers) and includes CSS that normalizes HTML5 elements, typography, lists, embedded content, forms, and tables.

Despite the project being based on the principle of normalization, it uses pragmatic defaults where they are preferable.

Normalize vs Reset

It’s worth understanding in greater detail how normalize.css differs from traditional CSS resets.

Normalize.css preserves useful defaults

Resets impose a homogenous visual style by flattening the default styles for almost all elements. In contrast, normalize.css retains many useful default browser styles. This means that you don’t have to redeclare styles for all the common typographic elements.

When an element has different default styles in different browsers, normalize.css aims to make those styles consistent and in line with modern standards when possible.

Normalize.css corrects common bugs

It fixes common desktop and mobile browser bugs that are out of scope for resets. This includes display settings for HTML5 elements, correcting font-size for preformatted text, SVG overflow in IE9, and many form-related bugs across browsers and operating systems.

For example, this is how normalize.css makes the new HTML5 search input type cross-browser consistent and stylable:

/**
 * 1. Addresses appearance set to searchfield in S5, Chrome
 * 2. Addresses box-sizing set to border-box in S5, Chrome (include -moz to future-proof)
 */

input[type="search"] {
  -webkit-appearance: textfield; /* 1 */
  -moz-box-sizing: content-box;
  -webkit-box-sizing: content-box; /* 2 */
  box-sizing: content-box;
}

/**
 * Removes inner padding and search cancel button in S5, Chrome on OS X
 */

input[type="search"]::-webkit-search-decoration,
input[type="search"]::-webkit-search-cancel-button {
  -webkit-appearance: none;
}

Resets often fail to bring browsers to a level starting point with regards to how an element is rendered. This is particularly true of forms – an area where normalize.css can provide some significant assistance.

Normalize.css doesn’t clutter your debugging tools

A common irritation when using resets is the large inheritance chain that is displayed in browser CSS debugging tools.

This is not such an issue with normalize.css because of the targeted styles and the conservative use of multiple selectors in rulesets.

Normalize.css is modular

The project is broken down into relatively independent sections, making it easy for you to see exactly which elements need specific styles. Furthermore, it gives you the potential to remove sections (e.g., the form normalizations) if you know they will never be needed by your website.

Normalize.css has extensive documentation

The normalize.css code is based on detailed cross-browser research and methodical testing. The file is heavily documented inline and further expanded upon in the GitHub Wiki. This means that you can find out what each line of code is doing, why it was included, what the differences are between browsers, and more easily run your own tests.

The project aims to help educate people on how browsers render elements by default, and make it easier for them to be involved in submitting improvements.

How to use normalize.css

First, install or download normalize.css from GitHub. There are then 2 main ways to make use of it.

Approach 1: use normalize.css as a starting point for your own project’s base CSS, customising the values to match the design’s requirements.

Approach 2: include normalize.css untouched and build upon it, overriding the defaults later in your CSS if necessary.

Closing comments

Normalize.css is significantly different in scope and execution to CSS resets. It’s worth trying it out to see if it fits with your development approach and preferences.

The project is developed in the open on GitHub. Anyone can report issues and submit patches. The full history of the project is available for anyone to see, and the context and reasoning for all changes can be found in the commit messages and the issue threads.

Related reading

Detailed information on default UA styles: WHATWG suggestions for rendering HTML documents, Internet Explorer User Agent Style Sheets,and CSS2.1 User Agent Style Sheet Defaults.

Translations

• Про normalize.css
• About normalize.css (Italiano)
• 关于Normalize.css

A new image replacement technique was recently added to the HTML5 Boilerplate project. This post explains how it works and how it compares to alternative image replacement techniques.

[15 December 2012] This technique is no longer used in HTML5 Boilerplate. It’s been replaced by another, more reliable approach.

Here’s the CSS behind the recent update to the image replacement helper class in HTML5 Boilerplate. It has also made its way into the Compass framework.

.ir {
  font: 0/0 a;
  text-shadow: none;
  color: transparent;
}

What does each declaration do?

• font:0/0 a – a shorthand property that zeros out the font size and line-height. The a value acts as a very short font-family (an idea taken from the BEM implementation of this method). The CSS validator complains that using 0/0 in the shorthand font property is not valid, but every browser accepts it and this appears to be an error in the validator. Using font:0px/0 a passes validation but it displayed as font:0/0 a in the code that the validator flags as valid.
• text-shadow:none – makes sure that any inherited text shadow is removed for the text. This prevents the chance of any text shadow colors showing over the background.
• color:transparent – needed for browsers than don’t completely crush the text to the point of being invisible. Safari 4 (extremely rare) is an example of such a browser. There may also be mobile browsers than require this declaration. IE6/7/8 don’t recognise this value for color, but fortunately IE7/8 don’t show any trace of the text. IE6 shows a faint trace.

In the HTML5 Boilerplate image replacement helper, we’ve also removed any border and background-color that may be on the element. This makes it easier to use the helper class on elements like button or with links that may included background or border properties as part of a design decision.

Benefits over text-indent methods

The new technique avoids various problems with any text-indent method, including the one proposed by Scott Kellum to avoid iPad 1 performance problems related to large negative text indents.

• Works in IE6/7 on inline-block elements. Techniques based on text indentation are basically “broken”, as shown by this test case: http://jsfiddle.net/necolas/QZvYa/show/
• Doesn’t result in any offscreen box being created. The text-indent methods result in a box being drawn (sometimes offscreen) for any text that have been negatively or positively indented. It can sometimes cause performance problems but the font-based method sidesteps those concerns.
• No need to specify a text-alignment and hide the overflow since the text is crushed to take up no space.
• No need to hide br or make all fallback HTML display:inline to get around the constraints of using a text indentation. This method is not affected by those problems.
• Fewer styles are needed as a result of these improvements.

Drawbacks

No image replacement hack is perfect.

• Leaves a very small trace of the text in IE6.
• This approach means that you cannot use em units for margins on elements that make use of this image replacement code. This is because the font size is set to 0.
• Windows-Eyes has a bug that prevents the reading of text hidden using this method. There are no problems with all other screenreaders that have been tested. Thanks to @jkiss for providing these detailed results and to @wilto for confirming this technique works for JAWS 12 in IE 6/7/8 and Firefox 4/5/6.
• Like so many IR methods, it doesn’t work when CSS is loaded but images are not.
• Text may not be hidden if a visitor is using a user style sheet which has explicitly set important font-size declarations for the element type on which you have applied the IR class.

It’s worth noting that the NIR image replacement technique avoids these drawbacks, but lacks support in IE6/7.

Closing comments

I’ve been using this technique without significant problems for nearly a year, ever since Jonathan Neal and I used it in a clearfix experiment. The BEM framework also makes use of it for their icon components. The core idea was even proposed back in 2003 but the browser quirks of the day may have prevented wider use.

If you come across any problems with this technique, please report them at the HTML5 Boilerplate GitHub issue tracker and include a test case when appropriate.

Translations

• Nouvelle méthode de remplacement de texte par une image

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