[scroll-animations-1] Improve introduction.

fantasai · fantasai · commit d618d513fb0e · 2022-11-18T15:34:45.000-05:00
diff --git a/scroll-animations-1/Overview.bs b/scroll-animations-1/Overview.bs
@@ -47,15 +47,22 @@ spec: cssom-view-1; type: dfn;
 	These <dfn>scroll-driven animations</dfn>
 	use a timeline based on scroll position,
 	rather than one based on clock time.
-	Animations are linked to such a timeline
-	using the CSS 'animation-timeline' property
-	or the Web Animations API.
+	This module provides both an imperative API building on the Web Animations API
+	as well as a declarative API building on CSS Animations.
 	<!-- [[!CSS-ANIMATIONS-2]] bikeshed chokes on this -->
 	[[!WEB-ANIMATIONS-1]]
 
 	There are two types of scroll-driven timelines:
-	* [=scroll progress timelines=]
-	* [=view progress timelines=]
+	* [[#scroll-timelines|Scroll Progress Timelines]],
+		which are linked to the scroll progress of a particular [=scroll container=]
+	* [[#view-timelines|View Progress Timelines]],
+		which are linked to the view progress of a particular [=box=] through a [=scrollport=]
+
+	Note: [=Scroll-driven animations=],
+	whose progress is linked to the scroll position,
+	are distinct from scroll-triggered animations,
+	which are triggered by a scroll position,
+	but whose progress is driven by time.
 
 ## Relationship to other specifications ## {#other-specs}
 
