[HTML5 Boilerplate homepage](http://html5boilerplate.com) | [Documentation
table of contents](README.md)

# The HTML

## Conditional `html` classes

A series of IE conditional comments apply the relevant IE-specific classes to
the `html` tag. This provides one method of specifying CSS fixes for specific
legacy versions of IE. While you may or may not choose to use this technique in
your project code, HTML5 Boilerplate's default CSS does not rely on it.

When using the conditional classes technique, applying classes to the `html`
element has several benefits:

* It avoids a [file blocking
  issue](http://webforscher.wordpress.com/2010/05/20/ie-6-slowing-down-ie-8/)
  discovered by Stoyan Stefanov and Markus Leptien.
* It avoids the need for an empty comment that also fixes the above issue.
* CMSes like WordPress and Drupal use the body class more heavily. This makes
  integrating there a touch simpler.
* It still validates as HTML5.
* It uses the same element as Modernizr (and Dojo). That feels nice.
* It can improve the clarity of code in multi-developer teams.


## The `no-js` class

Allows you to more easily explicitly add custom styles when JavaScript is
disabled (`no-js`) or enabled (`js`). More here: [Avoiding the
FOUC](http://paulirish.com/2009/avoiding-the-fouc-v3/).


## The order of meta tags, and `<title>`

As recommended by [the HTML5
spec](http://www.whatwg.org/specs/web-apps/current-work/complete/semantics.html#charset)
(4.2.5.5 Specifying the document's character encoding), add your charset
declaration early (before any ASCII art ;) to avoid a potential
[encoding-related security
issue](http://code.google.com/p/doctype/wiki/ArticleUtf7) in IE. It should come
in the first [1024
bytes](http://www.whatwg.org/specs/web-apps/current-work/multipage/semantics.html#charset).

The charset should also come before the `<title>` tag, due to [potential XSS
vectors](http://code.google.com/p/doctype-mirror/wiki/ArticleUtf7).

The meta tag for compatibility mode [needs to be before all elements except
title and meta](http://h5bp.com/f "Defining Document Compatibility - MSDN").
And that same meta tag can only be invoked for Google Chrome Frame if it is
within the [first 1024
bytes](http://code.google.com/p/chromium/issues/detail?id=23003).


## X-UA-Compatible

This makes sure the latest version of IE is used in versions of IE that contain
multiple rendering engines. Even if a site visitor is using IE8 or IE9, it's
possible that they're not using the latest rendering engine their browser
contains. To fix this, use:

```html
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
```

The `meta` tag tells the IE rendering engine two things:

1. It should use the latest, or edge, version of the IE rendering environment
2. If already installed, it should use the Google Chrome Frame rendering
   engine.

This `meta` tag ensures that anyone browsing your site in IE is treated to the
best possible user experience that their browser can offer.

This line breaks validation, and the Google Chrome Frame part won't work inside
a conditional comment. To avoid these edge case issues it is recommended that
you **remove this line and use the `.htaccess`** (or other server config)
to send these headers instead. You also might want to read [Validating:
X-UA-Compatible](http://groups.google.com/group/html5boilerplate/browse_thread/thread/6d1b6b152aca8ed2).

If you are serving your site on a non-standard port, you will need to set this
header on the server-side. This is because the IE preference option 'Display
intranet sites in Compatibility View' is checked by default.


## Mobile viewport

There are a few different options that you can use with the [`viewport` meta
tag](https://docs.google.com/present/view?id=dkx3qtm_22dxsrgcf4 "Viewport and
Media Queries - The Complete Idiot's Guide"). You can find out more in [the
Apple developer docs](http://j.mp/mobileviewport). HTML5 Boilerplate comes with
a simple setup that strikes a good balance for general use cases.

```html
<meta name="viewport" content="width=device-width">
```

## Favicons and Touch Icons

The shortcut icons should be put in the root directory of your site. HTML5
Boilerplate comes with a default set of icons (include favicon and Apple Touch
Icons) that you can use as a baseline to create your own.

If your site or icons are in a sub-directory, you will need to reference the
icons using `link` elements placed in the HTML `head` of your document.

For a comprehensive overview, please read [Everything you always wanted to know
about touch icons](http://mathiasbynens.be/notes/touch-icons) by Mathias
Bynens.


## Modernizr

HTML5 Boilerplate uses a custom build of Modernizr.

[Modernizr](http://modernizr.com) is a JavaScript library which adds classes to
the `html` element based on the results of feature test and which ensures that
all browsers can make use of HTML5 elements (as it includes the HTML5 Shiv).
This allows you to target parts of your CSS and JavaScript based on the
features supported by a browser.

In general, in order to keep page load times to a minimum, it's best to call
any JavaScript at the end of the page because if a script is slow to load
from an external server it may cause the whole page to hang. That said, the
Modernizr script *needs* to run *before* the browser begins rendering the page,
so that browsers lacking support for some of the new HTML5 elements are able to
handle them properly. Therefore the Modernizr script is the only JavaScript
file synchronously loaded at the top of the document.


## The content area

The central part of the boilerplate template is pretty much empty. This is
intentional, in order to make the boilerplate suitable for both web page and
web app development.

### Google Chrome Frame

The main content area of the boilerplate includes a prompt to install Chrome
Frame (which no longer requires administrative rights) for users of IE 6. If
you intended to support IE 6, then you should remove the snippet of code.

### Google CDN for jQuery

The Google CDN version of the jQuery JavaScript library is referenced towards
the bottom of the page using a protocol-independent path (read more about this
in the [FAQ](faq.md). A local fallback of jQuery is included for rare instances
when the CDN version might not be available, and to facilitate offline
development.

Regardless of which JavaScript library you choose to use, it is well worth the
time and effort to look up and reference the Google CDN (Content Delivery
Network) version. Your users may already have this version cached in their
browsers, and Google's CDN is likely to deliver the asset faster than your
server.

### Google Analytics Tracking Code

Finally, an optimized version of the latest Google Analytics tracking code is
included. Google recommends that this script be placed at the top of the page.
Factors to consider: if you place this script at the top of the page, you’ll be
able to count users who don’t fully load the page, and you’ll incur the max
number of simultaneous connections of the browser.

Further information:

* [Optimizing the asynchronous Google Analytics
  snippet](http://mathiasbynens.be/notes/async-analytics-snippet).
* [Tracking Site Activity - Google
  Analytics](http://code.google.com/apis/analytics/docs/tracking/asyncTracking.html).