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

In fact, these two methods may be combined. Only one whitespace character
is ignored after a hexadecimal escape. Note that this means that a
"real" space after the escape sequence must itself either be escaped or
doubled.
Backslash escapes are always considered to be part of an identifier [p. 38]
or a string (i.e., "\7B" is not punctuation, even though "{" is, and "\32" is
allowed at the start of a class name, even though "2" is not).
4.1.4 Statements
A CSS style sheet, for any version of CSS, consists of a list of statements (see
the grammar above). There are two kinds of statements: at-rules and rule sets.
There may be whitespace [p. 37] around the statements.
In this specification, the expressions "immediately before" or "immediately
after" mean with no intervening whitespace or comments.
4.1.5 At-rules
At-rules start with an at-keyword, an ’@’ character followed immediately by an
identifier [p. 38] (for example, ’@import’, ’@page’).
An at-rule consists of everything up to and including the next semicolon (;) or
the next block, [p. 40] whichever comes first. A CSS user agent that encounters
an unrecognized at-rule must ignore [p. 42] the whole of the at-rule and continue
parsing after it.
CSS2 user agents must ignore [p. 42] any ’@import’ [p. 71] rule that occurs
inside a block [p. 40] or that doesn’t precede all rule sets.
Illegal example(s):
Assume, for example, that a CSS2 parser encounters this style sheet:
@import "subs.css";
H1 { color: blue }
@import "list.css";
The second ’@import’ is illegal according to CSS2. The CSS2 parser ignores
[p. 42] the whole at-rule, effectively reducing the style sheet to:
@import "subs.css";
H1 { color: blue }
Illegal example(s):
In the following example, the second ’@import’ rule is invalid, since it occurs
inside a ’@media’ block [p. 40] .
@import "subs.css";
@media print {
@import "print-main.css";
BODY { font-size: 10pt }
}
H1 {color: blue }
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