andruud · andruud · May 23, 2024 · May 23, 2024 · May 27, 2024 · May 27, 2024
diff --git a/css-align-3/Overview.bs b/css-align-3/Overview.bs
@@ -771,7 +771,9 @@ Distributed Alignment: the ''<content-distribution>/stretch'', ''space-between''
 
 	These values are represented with the <<content-distribution>> grammar term:
 
-	<pre class='prod'><dfn>&lt;content-distribution></dfn> = space-between | space-around | space-evenly | stretch</pre>
+	<pre class='prod'>
+	<dfn>&lt;content-distribution></dfn> = space-between | space-around | space-evenly | stretch
+	</pre>
 
 <h3 id='overflow-values'>
 Overflow Alignment: the ''safe'' and ''unsafe'' keywords and scroll safety limits</h3>
@@ -865,31 +867,86 @@ Overflow Alignment: the ''safe'' and ''unsafe'' keywords and scroll safety limit
 		<dt>(no value specified)
 		<dd>
 			If the <a>overflow alignment</a> isn't explicitly specified,
-			the default <a>overflow alignment</a> is a blend of “safe” and “unsafe”
-			in that an overflowing <a>alignment subject</a> is allowed to overflow its <a>alignment container</a>,
-			but if this would cause it to also overflow
-			the <a>scrollable overflow area</a> of its nearest ancestor <a>scroll container</a>
-			(thus extending into the “unscrollable” region),
-			then its overflow in that direction is limited
-			by biasing any remaining overflow to the opposite side.
-
-			Issue: It may not be Web-compatible to implement the “smart” default behavior
-			(though we hope so, and believe it to be likely),
-			so UAs should pass any feedback on this point to the WG.
-			UAs that have not implemented the “smart” default behavior
-			must behave as ''safe'' for 'align-content' on [=block containers=]
-			and ''unsafe'' otherwise.
+			the default <a>overflow alignment</a> is a blend of “safe” and “unsafe”.
+			See [[#auto-safety]] for details.
 	</dl>
 
 
-<!--
-                   ██████   ███████  ██    ██ ████████ ████████ ██    ██ ████████
- ██   ██          ██    ██ ██     ██ ███   ██    ██    ██       ███   ██    ██
-  ██ ██           ██       ██     ██ ████  ██    ██    ██       ████  ██    ██
-█████████ ███████ ██       ██     ██ ██ ██ ██    ██    ██████   ██ ██ ██    ██
-  ██ ██           ██       ██     ██ ██  ████    ██    ██       ██  ████    ██
- ██   ██          ██    ██ ██     ██ ██   ███    ██    ██       ██   ███    ██
-                   ██████   ███████  ██    ██    ██    ████████ ██    ██    ██
+<h4 id=auto-safety>
+Automatic Overflow Alignment Safety</h4>
+
+	If no [=overflow alignment=] mode is specified for a property,
+	the default behavior lies somewhere between ''safe'' and ''unsafe'',
+	and also varies by layout mode.
+
+<h5 id=auto-safety-scroll>
+Content Distribution for Scroll Containers</h5>
+
+	The default [=overflow alignment=] behavior
+	for [=content distribution=] on [=scroll containers=] is ''unsafe''.
+	Non-''normal'' values of the [=content distribution properties=] instead
+	alter the [=scrollable overflow area=] in order to allow access to the overflowing content.
+	See [[#overflow-scroll-position]].
+
+<h5 id=auto-safety-position>
+Self-Alignment for Absolutely Positioned Boxes</h5>
+
+	For [=absolutely positioned=] [=alignment subjects=] whose
+
+	* relevant [=self-alignment property=] is not ''justify-self/normal'' and
+	* whose 'inset-area' property successfully defines an [=inset-area grid=]
+
+	the default [=overflow alignment=] behavior is as follows:
+
+	1. If the [=alignment subject=] overflows its [=inset-modified containing block=]
+		(its normal [=alignment container=]),
+		but does not overflow its [=original containing block=]
+		align as specified (''unsafe'').
+	2. If the <em>size</em> of the [=alignment subject=]
+		fits within its [=original containing block=],
+		but its specified alignment would cause it to overflow the [=original containing block=],
+		it is instead shifted the minimum amount
+		to stay within the [=original containing block=]
+		while honoring the alignment as much as possible
+		(i.e., flush with the edge of the [=original containing block=]
+		it was trying to overflow over).
+	3. If the size of the [=alignment subject=]
+		overflows the [=original containing block=],
+		it is instead start-aligned within the [=original containing block=]
+		(similar to ''safe'').
+
+	(For [=absolutely-positioned=] [=alignment subjects=] that fail the above conditions,
+	see [[#auto-safety-defaults]].)
+
+<h5 id=auto-safety-default>
+All Other Alignment</h5>
+
+	For all other elements:
+
+	1. If the [=alignment subject=] overflows its [=alignment container=],
+		align as specified (''unsafe'').
+	2. If the [=alignment subject=] would overflow
+		the [=scrollable overflow area=] of its nearest ancestor [=scroll container=],
+		(thus extending into the “unscrollable” region),
+		then its overflow in that direction is limited
+		by biasing any remaining overflow to the opposite side.
+
+	Issue: It may not be Web-compatible to implement the “smart” default behavior
+	(though we hope so, and believe it to be likely),
+	so UAs should pass any feedback on this point to the WG.
+	UAs that have not implemented the “smart” default behavior
+	must behave as ''safe'' for 'align-content' on [=block containers=]
+	and ''unsafe'' otherwise.
+
+<!-- Big Text: *-content
+
+               ███▌   ███▌  █    █▌ █████▌ █████▌ █    █▌ █████▌
+ █   █        █▌  █▌ █▌  █▌ █▌   █▌   █▌   █▌     █▌   █▌   █▌
+  █ █         █▌     █▌  █▌ ██▌  █▌   █▌   █▌     ██▌  █▌   █▌
+███████ ████▌ █▌     █▌  █▌ █▌▐█ █▌   █▌   ████   █▌▐█ █▌   █▌
+  █ █         █▌     █▌  █▌ █▌  ██▌   █▌   █▌     █▌  ██▌   █▌
+ █   █        █▌  █▌ █▌  █▌ █▌   █▌   █▌   █▌     █▌   █▌   █▌
+               ███▌   ███▌  █▌   ▐▌   █▌   █████▌ █▌   ▐▌   █▌
 -->
 
 <h2 id='content-distribution'>
@@ -1116,6 +1173,9 @@ Overflow and Scroll Positions</h3>
 	of the <a>scroll container</a>
 	satisfies the [[#alignment-values|expected alignment]]
 	of the <a>alignment subject</a> and <a>alignment container</a>.
+	However, the [[css-scroll-snap-2#scroll-start-target-with-place-content|scroll-start-target]]
+	property, when present, overrides the <a>content-distribution properties</a>
+	in determining the <a>initial scroll position</a>.
 
 	Note: The presence of scrollbars can change the size of the [=scroll container’s=] content box,
 	and thus the size of the [=alignment container=]

diff --git a/css-anchor-position-1/Overview.bs b/css-anchor-position-1/Overview.bs
@@ -297,6 +297,20 @@ that should match an 'anchor-name' value elsewhere on the page,
 or the keyword ''implicit'',
 or nothing (a missing specifier).
 
+Note: The general rule captured by these conditions
+is that an element can only be an anchor
+if it's fully laid out
+before the positioned element that wants to reference it
+is laid out.
+CSS's layout rules provide some useful guarantees about this,
+depending on the anchor and positioned element's relationship
+with each other and their containing blocks.
+The list of conditions below
+exactly rephrases the stacking context rules
+into just what's relevant for this purpose,
+ensuring there is no possibly circularity
+in anchor positioning.
+
 <div algorithm>
 	To determine the <dfn>target [=anchor element=]</dfn>
 	given a querying element |query el|
@@ -339,17 +353,6 @@ or nothing (a missing specifier).
 		which can affect what elements can be [=anchor elements=]
 		for a given lookup.
 
-	Note: The general rule captured by these conditions
-	is that |el| must be fully laid out
-	before |query el| is laid out.
-	CSS's rules about the layout order of stacking contexts
-	give us assurances about this,
-	and the list of conditions above
-	exactly rephrases the stacking context rules
-	into just what's relevant for this purpose,
-	ensuring there is no possibly circularity
-	in anchor positioning.
-
 	Note: An 'anchor-name' defined by styles in one [=shadow tree=]
 	won't be seen by [=anchor functions=] in styles in a different [=shadow tree=],
 	preserving encapsulation.
@@ -384,6 +387,10 @@ or nothing (a missing specifier).
 		or a [=part-like pseudo-element=].
 
 	* |el| is not in the [=skipped contents=] of another element.
+
+	* |el| is in scope for |query el|,
+		per the effects of 'anchor-scope' on |query el|
+		or its ancestors.
 </div>
 
 <!-- Big Text: default
@@ -552,25 +559,53 @@ Its syntax is:
 		or is not an [=absolutely-positioned=] element,
 		this value has no effect.
 
-		Otherwise, the property selects a region of the [=inset-area grid=],
-		and makes that the element's [=containing block=].
+		Otherwise, it has the following effects:
+
+		* The property selects a region of the [=inset-area grid=],
+			and makes that the element's [=containing block=].
+			See [[#resolving-spans]] for details.
 
-		Note: This means that the [=inset properties=] specify offsets from the inset-area,
-		and some property values,
-		like ''max-height: 100%'',
-		will be relative to the inset-area as well.
+			Note: This means that the [=inset properties=] specify offsets from the inset-area,
+			and some property values,
+			like ''max-height: 100%'',
+			will be relative to the inset-area as well.
 
-		Additionally, the ''align-self/normal'' value for the [=self-alignment properties=]
-		behaves as either ''align-self/start'', ''align-self/end'',
-		or ''align-self/anchor-center'',
-		depending on the positioning of the region,
-		to give a good default alignment for the positioned element.
+		* The ''align-self/normal'' value for the [=self-alignment properties=]
+			behaves as either ''align-self/start'', ''align-self/end'',
+			or ''align-self/anchor-center'',
+			depending on the positioning of the region,
+			to give a good default alignment for the positioned element.
+			Again, see [[#resolving-spans]] for details.
 
-		See [[#resolving-spans]] for details on both of these effects.
+		* Any ''top/auto'' [=inset properties=] resolve to ''0''.
 
-		Also, any ''top/auto'' [=inset properties=] resolve to ''0''.
+		* The element is not considered to be in a [=legacy alignment mode=]
+			in either axis.
 </dl>
 
+<div class=note>
+	If the element overflows its 'inset-area' (and 'inset') -modified [=containing block=],
+	but would still fit within its [=original containing block=],
+	by default it will "shift" to stay within its [=original containing block=],
+	even if that violates its normal alignment.
+	See [[css-align-3#overflow-values]] for details.
+
+	This behavior makes it more likely
+	that positioned elements remain visible
+	and within their intended bounds,
+	even when their [=containing block=]
+	ends up smaller than anticipated.
+
+	For example, an ''inset-area: bottom span-right'' value
+	lets the positioned element stretch
+	from its anchors left edge
+	to its containing block's right edge,
+	and left-aligns it in that space by default.
+	But if the positioned element is larger than that space
+	(such as if the anchor is very close to the right edge of the screen),
+	it will shift leftwards to stay visible.
+</div>
+
 
 <h4 id=resolving-spans>
 Resolving <<inset-area>>s</h4>
@@ -713,7 +748,7 @@ The ''anchor()'' function resolves to a <<length>>.
 It is only valid to be used in the [=inset properties=].
 
 <pre class=prod>
-	&lt;anchor()> = anchor( <<anchor-element>>? <<anchor-side>>, <<length-percentage>>? )
+	&lt;anchor()> = anchor( <<anchor-element>>? && <<anchor-side>>, <<length-percentage>>? )
 	<dfn><<anchor-element>></dfn> = <<dashed-ident>>
 	<dfn><<anchor-side>></dfn> = inside | outside
 			   | top | left | right | bottom
@@ -911,18 +946,20 @@ in the relevant axis.
 
 Additionally,
 any ''top/auto'' [=inset properties=] resolve to ''0''.
-However, the [=available space=] for the positioned element in the relevant axis
-is reduced to the size of the largest rectangle
-that is centered on the [=default anchor element=]
-and doesn't overflow the [=inset-modified containing block=].
-(Possibly being zero-sized,
-if the anchor's center is not within the [=inset-modified containing block=].)
 
 If the element is not [=absolutely positioned=],
 or does not have a [=default anchor element=],
 this value behaves as ''<self-position>/center''
 and has no additional effect on how [=inset properties=] resolve.
 
+Note: Similar to 'inset-area',
+when using ''anchor-center'',
+if the anchor is too close to the edge of the element's
+[=original containing block=],
+by default it will "shift" from being purely centered,
+to instead remain within the [=original containing block=].
+See [[css-align-3#overflow-values]] for more details.
+
 
 <!-- Big Text: scroll
 
@@ -1067,12 +1104,12 @@ it makes the declaration referencing it [=invalid at computed-value time=].
 <!-- Big Text: visibility
 
 █▌   █▌ ████  ███▌  ████ ████▌  ████ █▌    ████ █████▌ █   ▐▌
-█▌   █▌  ▐▌  █▌  █▌  ▐▌  █▌  █▌  ▐▌  █▌     ▐▌    █▌   ▐▌  █
-█▌   █▌  ▐▌  █▌      ▐▌  █▌  █▌  ▐▌  █▌     ▐▌    █▌    █ ▐▌
-▐▌   █   ▐▌   ███▌   ▐▌  █████   ▐▌  █▌     ▐▌    █▌    ▐▌█
- █  ▐▌   ▐▌      █▌  ▐▌  █▌  █▌  ▐▌  █▌     ▐▌    █▌     █▌
- ▐▌ █    ▐▌  █▌  █▌  ▐▌  █▌  █▌  ▐▌  █▌     ▐▌    █▌     █▌
-  ▐█    ████  ███▌  ████ ████▌  ████ █████ ████   █▌     █▌
+█▌   █▌  ▐▌  █▌  █▌  ▐▌  █▌  █▌  ▐▌  █▌     ▐▌    █▌   ▐▌  █ 
+█▌   █▌  ▐▌  █▌      ▐▌  █▌  █▌  ▐▌  █▌     ▐▌    █▌    █ ▐▌ 
+▐▌   █   ▐▌   ███▌   ▐▌  █████   ▐▌  █▌     ▐▌    █▌    ▐▌█  
+ █  ▐▌   ▐▌      █▌  ▐▌  █▌  █▌  ▐▌  █▌     ▐▌    █▌     █▌  
+ ▐▌ █    ▐▌  █▌  █▌  ▐▌  █▌  █▌  ▐▌  █▌     ▐▌    █▌     █▌  
+  ▐█    ████  ███▌  ████ ████▌  ████ █████ ████   █▌     █▌  
 -->
 
 Conditional Hiding: the 'position-visibility' property {#position-visibility}
@@ -1237,7 +1274,7 @@ The ''anchor-size()'' Function {#anchor-size-fn}
 ------------------------------
 
 <pre class=prod>
-anchor-size() = anchor-size( <<anchor-element>>? <<anchor-size>>, <<length-percentage>>? )
+anchor-size() = anchor-size( [ <<anchor-element>> || <<anchor-size>> ]? , <<length-percentage>>? )
 <dfn><<anchor-size>></dfn> = width | height | block | inline | self-block | self-inline
 </pre>
 
@@ -1266,6 +1303,12 @@ according to either the [=writing mode=] of the element
 or the [=writing mode=] of the element's [=containing block=]
 (for ''anchor-size()/block'' and ''anchor-size()/inline'').
 
+If the <<anchor-size>> keyword is omitted,
+it defaults to behaving as whatever keyword
+matches the axis of the property that ''anchor-size()'' is used in.
+(For example, ''width: anchor-size()''
+is equivalent to ''width: anchor-size(width)''.)
+
 An ''anchor-size()'' function representing a [=valid anchor-size function=]
 resolves at [=computed value=] time
 (via [=style & layout interleaving=])
@@ -1337,7 +1380,7 @@ Giving Fallback Options: the 'position-try-options' property {#position-try-opti
 
 <pre class=propdef>
 Name: position-try-options
-Value: none | [ [<<dashed-ident>> || <<try-tactic>>] | inset-area( <<'inset-area'>> ) ]#
+Value: none | [ [<<dashed-ident>> || <<try-tactic>>] | <<'inset-area'>> ]#
 Initial: none
 Inherited: no
 Applies to: [=absolutely-positioned=] elements
@@ -1423,7 +1466,7 @@ Values have the following meanings:
 
 		Otherwise, does nothing.
 
-	: <dfn>inset-area( <<'inset-area'>> )</dfn>
+	: <dfn><<'inset-area'>></dfn>
 	::
 		Automatically creates a [=position option=]
 		composed solely of an 'inset-area' property

diff --git a/css-box-4/Overview.bs b/css-box-4/Overview.bs
@@ -373,7 +373,7 @@ Margins at Container Edges: the 'margin-trim' property {#margin-trim}
 
 	<pre class="propdef">
 		Name: margin-trim
-		Value: none | block | inline | [ block-start || inline-start || block-end || inline-end ]
+		Value: none | [ block || inline ] | [ block-start || inline-start || block-end || inline-end ]
 		Initial: none
 		Applies to: [=block containers=], [=multi-column containers=], [=flex containers=], [=grid containers=]
 		Inherited: no