diff -r 2c0af1c2e723 -r ab66951166f3 src/Pure/Thy/html.scala
--- a/src/Pure/Thy/html.scala	Thu Nov 29 15:07:18 2018 +0100
+++ b/src/Pure/Thy/html.scala	Thu Nov 29 15:17:51 2018 +0100
@@ -350,7 +350,7 @@
   /* fonts */
 
   def fonts_url(): String => String =
-    (for (entry <- Isabelle_Fonts.fonts(html = true))
+    (for (entry <- Isabelle_Fonts.fonts(hidden = true))
      yield (entry.name -> Url.print_file(entry.path.file))).toMap
 
   def fonts_dir(prefix: String)(ttf_name: String): String =
@@ -368,7 +368,7 @@
         (if (entry.is_italic) List("  font-style: italic;") else Nil) :::
         List("}"))
 
-    ("/* Isabelle fonts */" :: Isabelle_Fonts.fonts(html = true).map(font_face(_)))
+    ("/* Isabelle fonts */" :: Isabelle_Fonts.fonts(hidden = true).map(font_face(_)))
       .mkString("", "\n\n", "\n")
   }