[css-syntax] Literal tokens in grammars are ASCII case-insensitive.

Author: SimonSapin

css-syntax/Overview.html

@@ -2592,12 +2592,21 @@ <h2 data-level=7 id=rule-defs><span class=secno>7 </span><span class=content>
 <p>	Several types of tokens are written literally, without quotes:
 
 <p>	<ul>
-		<li>〈Ident〉s (such as <span class=css data-autolink=maybe>auto</span>, <span class=css data-autolink=maybe>disc</span>, etc.)
-		<li>〈at-keyword〉s, which are written as an @ character followed by the token's name, like "@media".
+		<li>〈ident〉s (such as <span class=css data-autolink=maybe>auto</span>, <span class=css data-autolink=maybe>disc</span>, etc), which are simply written as their value.
+		<li>〈at-keyword〉s, which are written as an @ character followed by the token's value, like "@media".
 		<li>〈function〉s, which are written as the function name followed by a ( character, like "translate(".
 		<li>The 〈colon〉 (written as <code>:</code>), 〈comma〉 (written as <code>,</code>), 〈semicolon〉 (written as <code>;</code>), 〈(〉, 〈)〉, 〈{〉, and 〈}〉s.
 	</ul>
 
+<p>	Tokens match if their value is an <a href=#ascii-case-insensitive>ASCII case-insensitive</a> match
+	for the value defined in the grammar.
+
+	<p class=note>
+		Although it is possible, with <a href=#escaping0>escaping</a>,
+		to construct an 〈ident〉 whose value starts with <code>@</code> or ends with <code>(</code>,
+		such a tokens is not an 〈at-keyword〉 or a 〈function〉
+		and does not match corresponding grammar definitions.
+
 <p>	〈delim〉s are written with their value enclosed in single quotes.
 	For example, a 〈delim〉 containing the "+" character is written as <code>'+'</code>.
 	Similarly, the 〈[〉 and 〈]〉s must be written in single quotes,
@@ -3208,6 +3217,7 @@ <h2 class="no-num no-ref" id=index><span class=content>
 <li>end of the range, <a href=#end-of-the-range title="section 4.3.15">4.3.15</a>
 <li>〈EOF〉, <a href=#eof title="section 5.2">5.2</a>
 <li>EOF character, <a href=#eof-character title="section 4.2">4.2</a>
+<li>escaping, <a href=#escaping0 title="section 2.1">2.1</a>
 <li>function, <a href=#function title="section 5">5</a>
 <li>get an encoding, <a href=#get-an-encoding title="section 3.2">3.2</a>
 <li>hex digit, <a href=#hex-digit title="section 4.2">4.2</a>

css-syntax/Overview.src.html

@@ -2473,12 +2473,21 @@ <h2 id='rule-defs'>
 	Several types of tokens are written literally, without quotes:
 
 	<ul>
-		<li>〈Ident〉s (such as ''auto'', ''disc'', etc.)
-		<li>〈at-keyword〉s, which are written as an @ character followed by the token's name, like "@media".
+		<li>〈ident〉s (such as ''auto'', ''disc'', etc), which are simply written as their value.
+		<li>〈at-keyword〉s, which are written as an @ character followed by the token's value, like "@media".
 		<li>〈function〉s, which are written as the function name followed by a ( character, like "translate(".
 		<li>The 〈colon〉 (written as <code>:</code>), 〈comma〉 (written as <code>,</code>), 〈semicolon〉 (written as <code>;</code>), 〈(〉, 〈)〉, 〈{〉, and 〈}〉s.
 	</ul>
 
+	Tokens match if their value is an <a>ASCII case-insensitive</a> match
+	for the value defined in the grammar.
+
+	<p class=note>
+		Although it is possible, with <a>escaping</a>,
+		to construct an 〈ident〉 whose value starts with <code>@</code> or ends with <code>(</code>,
+		such a tokens is not an 〈at-keyword〉 or a 〈function〉
+		and does not match corresponding grammar definitions.
+
 	〈delim〉s are written with their value enclosed in single quotes.
 	For example, a 〈delim〉 containing the "+" character is written as <code>'+'</code>.
 	Similarly, the 〈[〉 and 〈]〉s must be written in single quotes,