[css-values-3] Sync against L4

Author: fantasai

css-values-3/Overview.bs

@@ -747,6 +747,12 @@ Range Restrictions and Range Definition Notation</h3>
 	or in the property description,
 	then <code>[&minus;&infin;,&infin;]</code> is assumed.
 
+	Values of &minus;&infin; or &infin; must be written without units,
+	even if the value type uses units.
+	Values of ''0'' <em>can</em> be written without units,
+	even if the value type doesn't allow “unitless zeroes”
+	(such as <<time>>).
+
 	Note: At the time of writing,
 	the <a>bracketed range notation</a> is new;
 	thus in most CSS specifications
@@ -815,8 +821,9 @@ Real Numbers: the <<number>> type</h3>
 
 	When written literally,
 	a <dfn export>number</dfn> is either an <a>integer</a>,
-	or zero or more decimal digits followed by a dot (.) followed by one or more decimal digits
-	and optionally an exponent composed of "e" or "E" and an integer.
+	optionally, it can be concluded by the letter “e” or “E”
+	followed by an integer indicating the base-ten exponent
+	in <a href="https://en.wikipedia.org/wiki/Scientific_notation">scientific notation</a>.
 	It corresponds to the <<number-token>> production
 	in the <a href="https://www.w3.org/TR/css-syntax/">CSS Syntax Module</a> [[!CSS-SYNTAX-3]].
 	As with integers, the first character of a number
@@ -2237,6 +2244,9 @@ Changes</h2>
 		(<a href="https://github.com/w3c/csswg-drafts/issues/7439">Issue 7439</a>)
 	* Removed definition of <<length-number>>, since it is impossible to combine them with ''calc()''.
 		(<a href="https://github.com/w3c/csswg-drafts/issues/2789">Issue 2789</a>)
+	* Fixed definition of [=numbers=] to allow decimals in combination with scientific notation,
+		as originally intended and as defined in [[CSS-SYNTAX-3]].
+		(<a href="https://github.com/w3c/csswg-drafts/issues/7248">Issue 7248</a>)
 	* Editorial improvements.
 
 	Changes since the <a href="https://www.w3.org/TR/2019/CR-css-values-3-20190131/">31 January 2019 Candidate Recommendation</a> are: