[css-scrollbars] Fix "computed value" and "applies to" lines

Author: frivoal

css-scrollbars-1/Overview.bs

@@ -85,7 +85,7 @@ Initial: auto
 Inherited: yes
 Computed value: specified keyword or two computed colors
 Animation type: by computed value
-Applies to: boxes to which 'overflow' applies
+Applies to: [=scroll containers=]
 Percentages: n/a
 </pre>
 
@@ -180,9 +180,9 @@ Name: scrollbar-width
 Value: auto | thin | none
 Initial: auto
 Inherited: no
-Computed value: specified keyword or absolute length
+Computed value: specified keyword
 Animation type: by computed value
-Applies to: boxes to which 'overflow' applies
+Applies to: [=scroll containers=]
 Percentages: n/a
 </pre>