[css-align-3] Make baseline clamping sentence easier to read. w3c#7660

Author: fantasai

css-align-3/Overview.bs

@@ -2270,10 +2270,10 @@ Determining the Baselines of a Box</h2>
 	For the purposes of finding the baselines of a box,
 	it and all its in-flow descendants with a scrolling mechanism (see the 'overflow' property)
 	must be considered as if scrolled to their initial scroll position.
-	Furthermore, if, in the case of a <a>scroll container</a> box,
-	the resulting position of a first/last baseline
-	is past a box's end/start border edge,
-	its position is clamped to that border edge.
+	Additionally,
+	if the position of a [=scroll container=]’s first/last baseline
+	is outside its border edge,
+	that baseline’s position is clamped to the border edge.
 
 <h3 id='baseline-terms'>
 Baseline Alignment Grouping</h3>