Apply class kableExtra to all HTML functions
diff --git a/R/footnote.R b/R/footnote.R
index a05360f..bb48e0d 100644
--- a/R/footnote.R
+++ b/R/footnote.R
@@ -147,6 +147,7 @@
 
   out <- as_kable_xml(kable_xml)
   attributes(out) <- kable_attrs
+  if (!"kableExtra" %in% class(out)) class(out) <- c("kableExtra", class(out))
   return(out)
 }