[css-align] Fix some writing mode issues.

Author: tabatkins

css-align/Overview.bs

@@ -15,7 +15,7 @@ Previous Version: https://www.w3.org/TR/2013/WD-css3-align-20130514/
 Previous Version: https://www.w3.org/TR/2012/WD-css3-align-20120612/
 Abstract: This module contains the features of <a href="https://www.w3.org/TR/CSS/">CSS</a> relating to the alignment of boxes within their containers in the various CSS box layout models: block layout, table layout, flex layout, and grid layout. (The alignment of text and inline-level content is defined in [[CSS-TEXT-3]] and [[CSS-INLINE-3]].)
 Link Defaults: selectors-3 (dfn) first formatted line, css-flexbox-1 (dfn) flex line, css-multicol-1 (dfn) multi-column element, css-fonts-3 (dfn) first available font, css21 (property) max-width/max-height/min-width/min-height, css-writing-modes-3 (dfn) dominant baseline, css-position-3 (property) left, css-cascade-3 (value) initial
-Ignored Terms: table cell, stretch
+Ignored Terms: table cell, stretch, scrollable overflow region
 At Risk: ''last-baseline''
 </pre>
 
@@ -865,10 +865,10 @@ Inline/Main-Axis Alignment: the 'justify-self' property</h3>
 
 				If the box has non-''top/auto'' offsets in this axis,
 				and either 'margin' in this axis is ''margin/auto'',
-				an ''width/auto'' 'width' is treated as ''fill-available''
+				an ''width/auto'' 'width' ('height', for <a>vertical writing modes</a>) is treated as ''fill-available''
 				and ''margin/auto'' margins are treated as zero.
 				(Otherwise, when 'justify-content' is not ''justify-content/normal'',
-				''width: auto'' is treated as ''width/fit-content''
+				''width: auto'' (''height: auto'') is treated as ''width/fit-content''
 				and ''margin/auto'' margins are used for alignment
 				as in in-flow block-level layout.)
 		<tr>
@@ -985,10 +985,11 @@ Block/Cross-Axis Alignment: the 'align-self' property</h3>
 
 				If the box has non-''top/auto'' offsets in this axis,
 				and either 'margin' in this axis is ''margin/auto'',
-				an ''width/auto'' 'height' is treated as ''fill-available''
+				an ''width/auto'' 'height' ('width', for <a>vertical writing modes</a>)
+				is treated as ''fill-available''
 				and ''margin/auto'' margins are treated as zero.
 				(Otherwise, when 'align-content' is not ''align-content/normal'',
-				''height: auto'' is treated as ''height/fit-content''
+				''height: auto'' (''width: auto'') is treated as ''height/fit-content''
 				and ''margin/auto'' margins are used for alignment
 				as in in-flow block-level layout.)
 		<tr>
@@ -1075,7 +1076,8 @@ Baseline Self-Alignment</h3>
 		<dt>Flex Items:
 		<dd>
 			A <a>flex item</a> participates in first (last) <a>baseline self-alignment</a> in its flex line
-			if its computed 'align-self' is ''baseline'' (''last-baseline'').
+			if its <a>inline axis</a> is parallel to the <a>main axis</a>
+			and its computed 'align-self' is ''baseline'' (''last-baseline'').
 			See [[!CSS3-FLEXBOX]] for details.
 
 		<dt>Grid Items: