[css-conditional-3][editorial] Dfn terms for feature queries and supports queries to help cross-referencing.

Author: fantasai

css-conditional-3/Overview.bs

@@ -229,9 +229,12 @@ is applied.
 
 The <dfn at-rule id="at-ruledef-supports">@supports</dfn> rule is a conditional group
 rule whose condition tests whether the user agent supports CSS
-property:value pairs.  Authors can use it to write style sheets that use
+''property:value'' pairs.  Authors can use it to write style sheets that use
 new features when available but degrade gracefully when those features
-are not supported.  CSS has existing mechanisms for graceful
+are not supported.
+These queries are called <dfn export>feature queries</dfn> or (colloquially) <dfn export>supports queries</dfn>.
+
+Note: CSS has existing mechanisms for graceful
 degradation, such as ignoring unsupported properties or values, but
 these are not always sufficient when large groups of styles need to be
 tied to the support for certain features, as is the case for use of new