[css-view-transitions-1] Add a rendering-characteristic note about ou…

…t-of-viewport elements (#10616)

* [css-view-transitions-1] Add a rendering-characteristic note about out-of-viewport.

Closes #8282

* nit

css-view-transitions-1/Overview.bs

@@ -1770,6 +1770,12 @@ urlPrefix: https://wicg.github.io/navigation-api/; type: interface;
 			However, the captured image should include, at the very least, the contents of |element| that intersect with the [=snapshot containing block=].
 			Implementations may adjust the rasterization quality to account for elements with a large [=ink overflow area=] that are transformed into view.
 
+		* Implementations may also adjust the rasterization quality for elements whose [=ink overflow rectangle=] does not intersect with the [=snapshot containing block=].
+			To avoid a broken experience if the element ends up becoming visible, the captured image should include, at the very least, some low-quality representation of the contents rather than transparent pixels.
+
+			Note: This allows efficiency in resource usage and rasterization performance for elements that are away from the viewport and might not become visible at all,
+			while maintaining a visual effect close enough to the author's intent.
+
 		* [=list/For each=] |descendant| of [=shadow-including descendant=] {{Element}} and [=pseudo-element=] of |element|,
 			if |descendant| is [=captured in a view transition=],
 			then skip painting |descendant|.
@@ -1979,6 +1985,7 @@ Changes from <a href="https://www.w3.org/TR/2023/WD-css-view-transitions-1-20230
 * Fix algorithm for dispatching updateDOMCallback promise.
 * Scope view transition names to matching tree context. See <a href="https://github.com/w3c/csswg-drafts/issues/10145">issue 10145</a>.
 * Fix scoping to match name instead of element. See <a href="https://github.com/w3c/csswg-drafts/issues/10145">issue 10145</a>.
+* Add a rendering characteristics note about out-of-viewport elements. See <a href="https://github.com/w3c/csswg-drafts/issues/8282">issue 8282</a>.
 
 <h3 id="changes-since-2022-05-25">
 Changes from <a href="https://www.w3.org/TR/2023/WD-css-view-transitions-1-20230525/">2022-05-25 Working Draft</a>