2.5 The Outline Algorithm 27NOTEFor the same reason as with the nav block in the footer (see the following sec-
tion), the sidebar contains a heading h2 directly before the first Questionnaire
block, hidden via CSS with display: none. The sidebar format is float: right
with width: 20% and font-size: 0.9em. The striking feature of the sidebar is the
rounded bottom-right corner, which means it’s time to admit that the HTML5
blog also uses CSS3: The rounded corner is only one of two features used. The
CSS syntax for the class rounded-bottom-right looks like this:
.rounded-bottom-right {
-moz-border-radius: 0px 0px 20px 0px;
-webkit-border-radius: 0px 0px 20px 0px;
border-radius: 0px 0px 20px 0px;
}
The second feature is responsible for the subtle shadow of the four areas and is
defined as follows in the CSS file:
.shadow {
-moz-box-shadow: 4px 0px 10px -3px silver;
-webkit-box-shadow: 4px 0px 10px -3px silver;
box-shadow: 4px 0px 10px -3px silver;
}
The tripling of the CSS command through the prefixes -moz- and -webkit- is
conspicuous; it is caused by the fact that CSS3 is not yet in the Candidate Rec-
ommendation phase. Once it enters this stage of the standardization process,
only then will it be ensured that border-radius and box-shadow will no longer be
changed. Until then, the prefixes are maintained to show that the implementa-
tion could still contain small deviations from the standard.
If you want to learn more about these two eagerly awaited features of the
CSS3 specification, you will find further information here:
z http://www.w3.org/TR/css3-background/#the-border-radius
z http://www.w3.org/TR/css3-background/#box-shadow2.5 The Outline Algorithm
Even if the details for outlining a document sound rather complicated in the
specification, there is a simple idea behind outlining, which is a machine-read-
able summary of the underlying document structure. This structure is deter-
mined by a combination of so-called sectioning content—for example, body,