HTML and CSS Reference
In-Depth Information
The CSS specification for each property lists whether that property can
inherit and whether it will inherit its parent's value by default.
The Importance of Good HTML Roots
A foundation of strong structural and semantic markup is crucial
to making designing with CSS easy, readable, and maintainable.
Although every individual node in the document tree can be styled
explicitly, with the behavior of the cascade, specificity, and inheri-
tance, CSS was designed to take advantage of element context and
markup patterns. Poorly crafted markup doesn't provide the con-
textual clues or “hooks” for styling that good markup practices like
the appropriate use of
<div>
or
<section>
elements, a varied level of
headings, and using paragraphs rather than line breaks do.
Values come in four flavors depending on where and how they are being
referenced. You've already encountered computed values and specified
values: the third is the actual value.
■
Specified values
: These are the values as they were coded in the
CSS rules.
■
Computed values
: These are the values for a property as they are
calculated after applying the cascade and inheritance but before the
document is processed or rendered. Units like ems are calculated and
turned into fixed values (pixels for most devices), paths to files are
made absolute, and inherited values are inherited.
■
Used values
: After all the values are calculated and the document is
processed, the value of some other properties such as percentage or
auto
-based widths that rely on the dimensions of a parent element
