Remove default `a` and `a:visited` color normalizations.

Inclusion of these normalizations can result in unwanted or
unexpected consequences. This is because `a:visited` has a
specificity of 0,0,1,1. Therefore, the pseudo-class has to be
included in every author link-style with a lower specificity.

This is not expected behaviour when building up link styles from
the browser defaults. Very little is lost by removing the link
color normalization.
Clearing heading tests added to the demo
Normalize h1 font-size. Close #41

h1 nested in 'section' and 'article' elements has a smaller
font-size in Firefox, Chrome, and Safari. This introduces browser
consistency.
Minor comment cleanup.

Fix #50
Close #58
Normalize only the left margin of lists. Fix #49

Prevent the addition of vertical margins on nested lists without
interferred with author expectations when customising margins
directly on 'ul' or 'ol' selectors later in the stylesheet.

Left margin needs to be normalized to remove it from IE6/7.

Close #57
Remove excess padding from checkbox and radio inputs in IE7. Close #42
Add small improvements to `legend` normalization.

Remove the default padding. In theory, the correct normalization
would be to add the padding to IE6/7 rather than remove it from
all browsers. However, the most common use case is going to be
for legends within unstyled fieldsets, and the presence of 2px
of horizontal padding is likely to be unexpected.

Allow text wrapping in Firefox 3. Modify the default white-space
value to allow long legends to wrap. No simple fix to allow this
in IE6/7/8.
Remove search cancel button from search inputs on Mac OS X.

After normalizing the search input on OS X, the search cancel
pseudo-element is not always well positioned and is missing from
other UAs.
Remove scrollbar normalization. Fix #64 #65

The `html` scrollbar normalization can cause issues in Firefox
when certain techniques are used by JS plugins (e.g. modals).
Move font-family normalization from `body` to `html`. Close #62

Prevents the inability to override the font-family by setting it
on the `html` element later in the CSS.
Combine the two WebKit search input pseudo-element rules
Re-set cursor to default for disabled `input` and `button`.
Demo: add disabled input test and other minor updates.

Include an `input` and `button` disabled attribute style test.
Remove `initial-scale` from the meta viewport and add the `lang`
attribute to `html`.
Normalize headings

There are various inconsistencies surrounding headings that make
this change worth trialing. The font-size of headings in IE6/7
isn't relative to the root font-size (see #61). Modern browsers
set the `h1` font-size based on the depth of nesting in certain
HTML5 sectioning elements. This change overcomes both the issues.

At the same time, the margins are being normalized so that they
are consistent and `em`-based. If people need to customise the
heading font-size and margin, they can either edit normalize.css
directly or override later in the source. But at least any non-
customised headings will behave consistently now.

Close #41
Update CSS comments
Normalize lists
Update CSS comments

The margin of lists in IE6/7 is set by 'pt', not relative to the root font-size. This is contrary to the HTML5 spec and other modern browsers, including IE8+.

If people need to customize the list margin, they can either edit normalize.css directly or override later in the source. But at least any non-customised lists will behave consistently now.
Add interactive content tests to demo.html

Initial addition of a `details` and `summary` test to the demo.
These are new HTML5 elements and there is not yet widespread
browser implementation of their interactive functionality.
Remove `details` from the rule applying padding-left to lists.

No browsers apply left padding to `details` by default.
Manual merge with GitHub master branch