[css-cascade] de-dup heading ID

Author: fantasai

css-cascade-3/Overview.bs

@@ -649,8 +649,8 @@ Cascading</h2>
 	sorts them by their declaration’s precedence as determined below,
 	and outputs a single <a>cascaded value</a>.
 
-<h3 id="cascade-order">
-Cascade Order</h3>
+<h3 id="cascade-sort">
+Cascade Sorting Order</h3>
 
 	The cascade sorts declarations according to the following criteria,
 	in descending order of priority:

css-cascade-4/Overview.bs

@@ -762,8 +762,8 @@ Cascading</h2>
 	sorts them by their declaration’s precedence as determined below,
 	and outputs a single <a>cascaded value</a>.
 
-<h3 id="cascade-order">
-Cascade Order</h3>
+<h3 id="cascade-sort">
+Cascade Sorting Order</h3>
 
 	The cascade sorts declarations according to the following criteria,
 	in descending order of priority:

css-scoping-1/Overview.bs

@@ -435,7 +435,7 @@ Selecting Slot-Assigned Content: the ''::slotted()'' pseudo-element</h4>
 <h3 id='shadow-cascading'>
 Shadow Trees and the Cascade</h3>
 
-	See [[css-cascade-4#cascade-order]].
+	See [[css-cascade-4#cascade-sort]].
 
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