[css-text-decor-4] Add <percentage> values to text-underline-thickness and text-underline-offset. #2165

Author: fantasai

css-text-decor-4/Overview.bs

@@ -290,7 +290,7 @@ Text Decoration Line Thickness: the 'text-decoration-thickness' property</h3>
 
 	<pre class="propdef">
 	Name: text-decoration-thickness
-	Value: auto | from-font | <<length>>
+	Value: auto | from-font | <<length>> | <<percentage>>
 	Initial: auto
 	Applies to: all elements
 	Inherited: no
@@ -319,10 +319,19 @@ Text Decoration Line Thickness: the 'text-decoration-thickness' property</h3>
 
 		<dt><dfn><<length>></dfn>
 		<dd>
-			Specifies the thickness of text decoration lines as a length.
+			Specifies the thickness of text decoration lines as a fixed length.
 			The UA must floor the actual value at one device pixel.
-			Authors are strongly encouraged to use ''em'' units
-			so that the line thickness scales with the font.
+
+			Note: A length will inherit as a fixed value,
+			and will not scale with the font.
+
+		<dt><dfn><<percentage>>
+		<dd>
+			<p>Specifies the offset of underlines as a percentage of ''1em''.
+			The UA must floor the actual value at one device pixel.
+
+			Note: A percentage will inherit as a relative value,
+			and will therefore scale with changes in the font as it inherits.
 	</dl>
 
 <h4 id="text-decoration-thickness">
@@ -605,7 +614,7 @@ Text Underline Offset: the 'text-underline-offset' property</h3>
 
 	<pre class="propdef">
 	Name: text-underline-offset
-	Value: auto | <<length>>
+	Value: auto | <<length>> | <<percentage>>
 	Initial: auto
 	Applies to: all elements
 	Inherited: yes
@@ -637,6 +646,13 @@ Text Underline Offset: the 'text-underline-offset' property</h3>
 
 			Note: A length will inherit as a fixed value,
 			and will not scale with the font.
+
+		<dt><dfn><<percentage>>
+		<dd>
+			<p>Specifies the offset of underlines as a percentage of ''1em''.
+
+			Note: A percentage will inherit as a relative value,
+			and will therefore scale with changes in the font as it inherits.
 	</dl>
 
 	When the value of the 'text-decoration-line' property is either
@@ -1872,6 +1888,22 @@ Appendix B: Default UA Stylesheet</h2>
 <h2 class="no-num" id="changes">Appendix C:
 Changes</h2>
 
+<h3 class="no-num" id="changes-2018">
+Changes since the 13 March 2018 Working Draft</h3>
+
+<ul>
+	<li>Merged in entire contents of <a href="https://www.w3.org/TR/css-text-decor-3/">CSS Text Decoration Level 3</a>,
+	so that this is no longer a diff spec.
+	<li>Renamed <css>text-decoration-width</css> to 'text-decoration-thickness'.
+	<li>Defined 'text-underline-offset' postion values as outsets rather than insets,
+		because this was more intuitive to users.
+	<li>Moved ''text-underline-position/from-font'' keyword from 'text-underline-offset' to 'text-underline-position'.
+		(<a href="https://github.com/w3c/csswg-drafts/issues/3118#issuecomment-432297480">Issue 3118</a>)
+	<li>Added <<percentage>> values to 'text-decoration-thickness' and 'text-underline-offset'.
+		(<a href="https://github.com/w3c/csswg-drafts/issues/2165">Issue 2165</a>)
+	<li>
+</ul>
+
 <h3 class="no-num" id="additions-l3">
 Additions Since Level 3</h3>
 
@@ -1880,6 +1912,7 @@ The following features have been added since <a href="https://www.w3.org/TR/css-
 <ul>
 	<li>Added ''spelling-error'' and ''grammar-error'' values to 'text-decoration-line'.
 	<li>Added 'text-decoration-thickness' and 'text-underline-offset' properties.
+	<li>Added ''text-underline-position/from-font'' value to 'text-underline-position'.
 	<li>Drafted 'text-emphasis-skip' property.
 	<li>Added [=spread distance=] value to 'text-shadow'.
 </ul>