[css-snappoints] Rewording definition of length values for snap margin

Author: ChumpChief

css-snappoints/Overview.bs

@@ -389,13 +389,16 @@ Scroll Snap Margin: the 'scroll-snap-margin' property {#scroll-snap-margin}
 
     The 'scroll-snap-margin' property defines the <a>scroll snap margin</a> on elements within a <a>scroll container</a>, used in calculating <a>snap positions</a> for that scroll container.
 
-    <dl dfn-type="value" dfn-for="scroll-snap-margin">
-        <dt><dfn><<length>>{1,4}</dfn>
-        <dd>
-            Specifies the outset of the element's snap margin from the axis-aligned bounding box of the transformed border box, in the <a>scroll container's</a> coordinate space.  Outsets are applied to this bounding box, not the border box.
-
-            Note: This ensures that the <a>scroll snap margin</a> is always rectangular and axis-aligned to the <a>scroll container's</a> coordinate space.
-    </dl>
+    The 'scroll-snap-margin' property defines
+    the <dfn lt="scroll snap area" local-lt="snap area">scroll snap area</dfn>
+    that is used for snapping this box to the viewport.
+    The <<length>> values give outsets
+    (interpreted as for 'margin' or 'border-image-outset').
+    The <a>scroll snap area</a> is the rectangular bounding box of the transformed border box,
+    plus the specified outsets,
+    axis-aligned in the <a>scroll container’s</a> coordinate space.
+
+    Note: This ensures that the <a>scroll snap margin</a> is always rectangular and axis-aligned to the <a>scroll container's</a> coordinate space.
 
     This property is a <a>shorthand property</a> that sets all of the <a href="#longhands"><css>scroll-snap-margin-*</css> longhands</a> in one declaration.