W3C CSS2 Cascading Style Sheets, level 2 - instructional media + ...

Example(s):
The following rules have the same effect as if the imported style sheet were
wrapped in an @media rule for the same media, but it may save the UA a fruitless
download.
@import url("fineprint.css") print;
@import url("bluish.css") projection, tv;
In the absence of any media types, the import is unconditional. Specifying ’all’
for the medium has the same effect.
6.4 The cascade
Style sheets may have three different origins: author, user, and user agent.
Author. The author specifies style sheets for a source document according
to the conventions of the document language. For instance, in HTML, style
sheets may be included in the document or linked externally.
User: The user may be able to specify style information for a particular document.
For example, the user may specify a file that contains a style sheet or
the user agent may provide an interface that generates a user style sheet (or
behave as if it did).
User agent: Conforming user agents [p. 32] must apply a default style sheet
(or behave as if they did) prior to all other style sheets for a document. A
user agent’s default style sheet should present the elements of the document
language in ways that satisfy general presentation expectations for the
document language (e.g., for visual browsers, the EM element in HTML is
presented using an italic font). See "A sample style sheet for HTML 4.0"
[p. 291] for a recommended default style sheet for HTML 4.0 documents.
Note that the default style sheet may change if system settings are modified
by the user (e.g., system colors). However, due to limitations in a user
agent’s internal implementation, it may be impossible to change the values
in the default style sheet.
Style sheets from these three origins will overlap in scope, and they interact
according to the cascade.
The CSS cascade assigns a weight to each style rule. When several rules
apply, the one with the greatest weight takes precedence.
By default, rules in author style sheets have more weight than rules in user
style sheets. Precedence is reversed, however, for "!important" rules. All rules
user and author rules have more weight than rules in the UA’s default style
sheet.
Imported style sheets also cascade and their weight depends on their import
order. Rules specified in a given style sheet override rules imported from other
style sheets. Imported style sheets can themselves import and override other
style sheets, recursively, and the same precedence rules apply.
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