[css-inline-3] Define auto height calculations for atomic inlines to follow usual rules unless 'auto', in which case it follows initial-letter 'border-box' rules. #3231

Author: fantasai

css-inline-3/Overview.bs

@@ -953,6 +953,7 @@ Initial Letter Layout</h3>
 	which is either a <a>replaced element</a>
 	or which establishes an <a>independent formatting context</a> for its contents,
 	the sizing of the box
+	(aside from its <a>automatic size</a> in the <a>block axis</a>)
 	and layout of the contents within the box
 	follows the usual rules:
 	it is primarily the positioning of the box
@@ -1072,7 +1073,8 @@ Shaping and Glyph Selection</h4>
 <h3 id="initial-letter-box-size">
 Sizing the Initial Letter Box</h3>
 
-	If the <a>initial letter</a>’s <a>specified width</a>/<a>specified height</a>
+	For an <a>inline initial letter</a>,
+	if the <a>initial letter</a>’s <a>specified width</a>/<a>specified height</a>
 	is <a>definite</a>,
 	use that value
 	(clamped as required by the <a>min size</a> and <a>max size</a> properties,
@@ -1095,6 +1097,14 @@ Sizing the Initial Letter Box</h3>
 	with the hanging punctuation properly hanging)?
 	See <a href="https://github.com/w3c/csswg-drafts/issues/310">discussion</a>.
 
+	For <a>atomic initial letters</a>,
+	sizing follows the usual rules for that type of <a>atomic inline</a>.
+	However, if the box has an [=automatic size|automatic=] [=block size=] (''height/auto''),
+	then its <a>block size</a> is determined
+	as for an <a>inline initial letter</a>
+	with ''initial-letter-align/border-box'' alignment,
+	and is <a>definite</a>.
+
 <h4 id="initial-letter-content-align">
 Alignment Within an Initial Letter Box</h4>