Grammar fix

Fixes https://www.w3.org/Bugs/Public/show_bug.cgi?id=28846

source

@@ -69657,9 +69657,9 @@ contradict people?
   <p>The Selectors specification leaves the case-sensitivity of element names, attribute names, and
   attribute values to be defined by the host language. <ref spec=SELECTORS></p>
 
-  <p class="note">The Selectors specification defines that ID and class selectors, when matched
-  against elements in documents that are in <span>quirks mode</span>, will be work in an <span>ASCII
-  case-insensitive</span>.</p>
+  <p class="note"><cite>Selectors</cite> defines that ID and class selectors, when matched against
+  elements in documents that are in <span>quirks mode</span>, will be matched in an <span>ASCII
+  case-insensitive</span> manner.</p>
 
   <p>When comparing a CSS element type selector to the names of <span>HTML elements</span> in
   <span>HTML documents</span>, the CSS element type selector must first be <span>converted to ASCII