[css-align] Rename 'true' to 'unsafe', and remove the lingering mentions of default overflow alignment in individual layout modes.

Author: tabatkins

css-align/Overview.bs

@@ -382,7 +382,7 @@ Distributed Alignment: the ''<content-distribution>/stretch'', ''space-between''
 		Add even more example images.
 
 <h3 id='overflow-values'>
-Overflow Alignment: the ''safe'' and ''true'' keywords</h3>
+Overflow Alignment: the ''safe'' and ''unsafe'' keywords</h3>
 
 	When the <a>alignment subject</a> is larger than the <a>alignment container</a>,
 	it will overflow.
@@ -394,34 +394,29 @@ Overflow Alignment: the ''safe'' and ''true'' keywords</h3>
 
 	To help combat this problem,
 	an <dfn export>overflow alignment</dfn> mode can be explicitly specified.
-	"True" alignment honors the specified alignment mode in overflow situations, even if it causes data loss,
+	"Unsafe" alignment honors the specified alignment mode in overflow situations, even if it causes data loss,
 	while "safe" alignment changes the alignment mode in overflow situations in an attempt to avoid data loss.
 
 	If the <a>overflow alignment</a> isn't explicitly specified,
-	the default <a>overflow alignment</a> is ''true''.
+	the default <a>overflow alignment</a> is ''unsafe''.
 
-	<pre class='prod'><dfn>&lt;overflow-position></dfn> = true | safe</pre>
+	<pre class='prod'><dfn>&lt;overflow-position></dfn> = &lt; | safe</pre>
 
 	<dl dfn-type="value" dfn-for="<overflow-position>">
 		<dt><dfn>safe</dfn>
 		<dd>
 			If the size of the <a>alignment subject</a> overflows the <a>alignment container</a>,
 			the <a>alignment subject</a> is instead aligned as if the alignment mode were ''start''.
 
-		<dt><dfn>true</dfn>
+		<dt><dfn>unsafe</dfn>
 		<dd>
 			Regardless of the relative sizes of the <a>alignment subject</a> and <a>alignment container</a>,
 			the given alignment value is honored.
-
-			Issue: Calling one value "true" incorrectly makes one think of booleans.
-			Is there a better term to use here?
-			Or, now that ''true'' is the default,
-			can we just drop the keyword and let it be expressed by omission?
 	</dl>
 
 
 	<div class='example'>
-		The figure below illustrates the difference in "safe" versus "true" centering,
+		The figure below illustrates the difference in "safe" versus "unsafe" centering,
 		using a column flexbox as an example:
 
 		<figure>
@@ -463,12 +458,12 @@ Overflow Alignment: the ''safe'' and ''true'' keywords</h3>
 			</div>
 			<figcaption>
 				The items in the figure on the left are set to ''align-self: safe center;'',
-				while those in the figure on the right are set to ''align-self: true center;''.
+				while those in the figure on the right are set to ''align-self: unsafe center;''.
 				If this column <a>flex container</a> was placed against the left edge of the page,
 				the "safe" behavior would be more desirable,
 				as the long item would be fully readable.
 				In other circumstances,
-				the "true" centering behavior might be better,
+				the "unsafe" centering behavior might be better,
 				as it correctly centers all the items.
 			</figcaption>
 		</figure>
@@ -718,7 +713,6 @@ Inline/Main-Axis Alignment: the 'justify-self' property</h3>
 			(Note: This is the legacy behavior of HTML <code>align</code>.)
 			The <a>alignment subject</a> is the block's margin box.
 
-			The default <a>overflow alignment</a> is ''safe''.
 			In terms of CSS2.1 block-level formatting [[!CSS21]],
 			the rules for "over-constrained" computations in <a href="http://www.w3.org/TR/CSS21/visudet.html#blockwidth">section 10.3.3</a>
 			are ignored in favor of alignment as specified here
@@ -749,7 +743,6 @@ Inline/Main-Axis Alignment: the 'justify-self' property</h3>
 			as modified by the offset properties ('top'/'right'/'bottom'/'left').
 			The <a>alignment subject</a> is the box's margin box.
 
-			The default <a>overflow alignment</a> is ''safe''.
 			In terms of CSS2.1 formatting [[!CSS21]],
 			the rules for "over-constrained" computations in <a href="http://www.w3.org/TR/CSS21/visudet.html#abs-non-replaced-width">section 10.3.7</a>
 			are ignored in favor of alignment as specified here
@@ -773,7 +766,6 @@ Inline/Main-Axis Alignment: the 'justify-self' property</h3>
 
 			The <a>alignment container</a> is the <a>grid area</a>.
 			The <a>alignment subject</a> is the <a>grid item</a>’s margin box.
-			The default <a>overflow alignment</a> is ''true''.
 
 			''justify-self/normal'' behaves as ''justify-self/stretch''.
 	</dl>
@@ -849,7 +841,6 @@ Block/Cross-Axis Alignment: the 'align-self' property</h3>
 			as modified by the offset properties ('top'/'right'/'bottom'/'left').
 			The <a>alignment subject</a> is the box's margin box.
 
-			The default <a>overflow alignment</a> is ''safe''.
 			In terms of CSS2.1 formatting [[!CSS21]],
 			the rules for "over-constrained" computations in <a href="http://www.w3.org/TR/CSS21/visudet.html#abs-non-replaced-height">section 10.6.4</a>
 			are ignored in favor of alignment as specified here
@@ -870,7 +861,6 @@ Block/Cross-Axis Alignment: the 'align-self' property</h3>
 
 			The <a>alignment container</a> is the <a>flex line</a> the item is in.
 			The <a>alignment subject</a> is the <a>flex item</a>’s margin box.
-			The default <a>overflow alignment</a> is ''true''.
 			See [[!CSS3-FLEXBOX]] for details.
 
 			''align-self/normal'' behaves as ''align-self/stretch''.
@@ -881,7 +871,6 @@ Block/Cross-Axis Alignment: the 'align-self' property</h3>
 
 			The <a>alignment container</a> is the <a>grid area</a>.
 			The <a>alignment subject</a> is the <a>grid item</a>’s margin box.
-			The default <a>overflow alignment</a> is ''true''.
 
 			''align-self/normal'' behaves as ''align-self/stretch''.
 	</dl>