[css-values-4] Add lv* units explicitly for large viewport size. w3c#4329

Author: fantasai

css-values-4/Overview.bs

@@ -1737,11 +1737,6 @@ Font-relative Lengths: the ''em'', ''ex'', ''cap'', ''ch'', ''ic'', ''rem'', ''l
 <h4 id="viewport-relative-lengths">
 Viewport-percentage Lengths: the ''*vw'', ''*vh'', ''*vi'', ''*vb'', ''*vmin'', ''*vmax'' units</h4>
 
-	ISSUE: <img src="../construction.gif" alt="" style="float: right">
-	This section is <strong>UNDER CONSTRUCTION</strong>.
-	Please use <a href="https://www.w3.org/TR/css-values-3/">CSS Values and Units Level 3</a>
-	as an implementation reference for now.
-
 	The <dfn export>viewport-percentage lengths</dfn> are relative to the size of the
 	<a href="https://www.w3.org/TR/CSS21/visudet.html#containing-block-details">initial containing block</a>--
 	which is itself based on the size of either
@@ -1753,13 +1748,32 @@ Viewport-percentage Lengths: the ''*vw'', ''*vh'', ''*vi'', ''*vb'', ''*vmin'',
 <h5 id="viewport-variants" class="no-toc">
 The Large, Small, and Dynamic Viewport Sizes</h5>
 
-	There are three variants of the [=viewport-percentage length=] units,
-	corresponding to three (possibly identical) notions of the viewport size.
+	There are four variants of the [=viewport-percentage length=] units,
+	corresponding to four (possibly identical) notions of the viewport size.
 
 	<dl export>
+		<dt>UA-default viewport
+		<dd>
+			The <dfn export>UA-default viewport-percentage units</dfn>
+			(''v*'')
+			are defined with respect to a UA-defined <dfn export>UA-default viewport size</dfn>,
+			which for any given document
+			should be equivalent to the [=large viewport size=],
+			[=small viewport size=],
+			or some intermediary size.
+
+			ISSUE: Should the [=UA-default viewport size=] be required
+			to correspond to the size of the [=initial containing block=]?
+
+			Note: Implementations that choose a size other than
+			the [=large viewport size=] or [=small viewport size=]
+			are encouraged to explain their choice to the CSSWG
+			for consideration in future specification updates.
+
 		<dt>large viewport
 		<dd>
 			The <dfn export>large viewport-percentage units</dfn>
+			(''lv*'')
 			are defined with respect to the <dfn export>large viewport size</dfn>:
 			the viewport sized assuming
 			any UA interfaces that are dynamically expanded and retracted
@@ -1789,6 +1803,7 @@ The Large, Small, and Dynamic Viewport Sizes</h5>
 		<dt>small viewport
 		<dd>
 			The <dfn export>small viewport-percentage units</dfn>
+			(''sv*'')
 			are defined with respect to the <dfn export>small viewport size</dfn>:
 			the viewport sized assuming
 			any UA interfaces that are dynamically expanded and retracted
@@ -1818,6 +1833,7 @@ The Large, Small, and Dynamic Viewport Sizes</h5>
 		<dt>dynamic viewport
 		<dd>
 			The <dfn export>dynamic viewport-percentage units</dfn>
+			(''dv*'')
 			are defined with respect to the <dfn export>dynamic viewport size</dfn>:
 			the viewport sized
 			with dynamic consideration of any UA interfaces
@@ -1879,11 +1895,13 @@ The Various Viewport-relative Units</h5>
 	<dl export dfn-type=value dfn-for="<length>">
 		<dt><dfn lt="vw">vw unit</dfn>
 		<dt><dfn lt="svw">svw unit</dfn>
+		<dt><dfn lt="lvw">lvw unit</dfn>
 		<dt><dfn lt="dvw">dvw unit</dfn>
 		<dd>
 			Equal to 1% of the width of the
-			[=large viewport size=],
+			[=UA-default viewport size=],
 			[=small viewport size=],
+			[=large viewport size=],
 			and [=dynamic viewport size=],
 			respectively.
 
@@ -1897,16 +1915,19 @@ The Various Viewport-relative Units</h5>
 
 		<dt><dfn lt="vh">vh unit</dfn>
 		<dt><dfn lt="svh">svh unit</dfn>
+		<dt><dfn lt="lvh">lvh unit</dfn>
 		<dt><dfn lt="dvh">dvh unit</dfn>
 		<dd>
 			Equal to 1% of the height of the
-			[=large viewport size=],
+			[=UA-default viewport size=],
 			[=small viewport size=],
+			[=large viewport size=],
 			and [=dynamic viewport size=],
 			respectively.
 
 		<dt><dfn lt=vi>vi unit</dfn>
 		<dt><dfn lt=svi>svi unit</dfn>
+		<dt><dfn lt=lvi>lvi unit</dfn>
 		<dt><dfn lt=dvi>dvi unit</dfn>
 		<dd>
 			Equal to 1% of the size of the
@@ -1918,23 +1939,27 @@ The Various Viewport-relative Units</h5>
 
 		<dt><dfn lt=vb>vb unit</dfn>
 		<dt><dfn lt=svb>svb unit</dfn>
+		<dt><dfn lt=lvb>lvb unit</dfn>
 		<dt><dfn lt=dvb>dvb unit</dfn>
 		<dd>
 			Equal to 1% of the size of the initial containing block
-			[=large viewport size=],
+			[=UA-default viewport size=],
 			[=small viewport size=],
+			[=large viewport size=],
 			and [=dynamic viewport size=]
 			(respectively)
 			in the direction of the root element's block axis.
 
 		<dt><dfn lt="vmin">vmin unit</dfn>
 		<dt><dfn lt="svmin">svmin unit</dfn>
+		<dt><dfn lt="lvmin">lvmin unit</dfn>
 		<dt><dfn lt="dvmin">dvmin unit</dfn>
 		<dd>
 			Equal to the smaller of ''*vw'' or ''*vh''.
 
 		<dt><dfn lt="vmax">vmax unit</dfn>
 		<dt><dfn lt="svmax">svmax unit</dfn>
+		<dt><dfn lt="lvmax">lvmax unit</dfn>
 		<dt><dfn lt="dvmax">dvmax unit</dfn>
 		<dd>
 			Equal to the larger of ''*vw'' or ''*vh''.
@@ -1967,10 +1992,6 @@ The Various Viewport-relative Units</h5>
 	but can also block critical content (such as toolbars, headers, and footers) in others.
 	It's therefore not entirely clear whether this is the best mapping.
 
-	ISSUE: Should we have dedicated ''lv*'' units for the [=large viewport size=]?
-	That would give authors an explicit version, and allow the unprefixed units
-	to maybe do smarter things to avoid obscuring critical content.
-
 	In situations where there is no root element
 	or it hasn't yet been styled
 	(such as when evaluating <a>media queries</a>),
@@ -4921,7 +4942,8 @@ Recent Changes</h3>
 
 	<ul>
 		<li>Updated interpolation of colors to reference [[CSS-COLOR-4]] instead of [[CSS-COLOR-3]].
-		<li>Added the ''svh'', ''svw'', ''svi'', ''svb'', ''svmin'', and ''svmax'' [=small viewport-percentage units=]
+		<li>Added the ''svh'', ''svw'', ''svi'', ''svb'', ''svmin'', and ''svmax'' [=small viewport-percentage units=];
+			''lvh'', ''lvw'', ''lvi'', ''lvb'', ''lvmin'', and ''lvmax'' [=large viewport-percentage units=];
 			and ''dvh'', ''dvw'', ''dvi'', ''dvb'', ''dvmin'', and ''dvmax'' [=dynamic viewport-percentage units=].
 			(<a href="https://github.com/w3c/csswg-drafts/issues/4329">Issue 4329</a> and
 			 <a href="https://github.com/w3c/csswg-drafts/issues/6113">Issue 6113</a>)