autodoc: Extract decl ref style and fix light mode color (#15990)

Co-authored-by: James Chen-Smith <james@chen-smith.net>
Co-authored-by: Loris Cro <kappaloris@gmail.com>

lib/docs/index.html

@@ -649,6 +649,10 @@
           color: #458;
           font-weight: bold;
       }
+      .tok-decl-ref {
+          color: #0086b3;
+          font-weight: bold;
+      }
 
       /* dark mode */
       @media (prefers-color-scheme: dark) {
@@ -723,6 +727,9 @@
         .tok-type {
             color: #68f;
         }
+        .tok-decl-ref {
+            color: lightblue;
+        }
       }
 
       @media only screen and (max-width: 750px) {