diff --git a/config/_default/markup.toml b/config/_default/markup.toml
index 1202e5b..5241889 100644
--- a/config/_default/markup.toml
+++ b/config/_default/markup.toml
@@ -3,19 +3,25 @@
 
 # let us put inline html into the markdown files
 [goldmark]
-[goldmark.renderer]
-  unsafe = true
+  [goldmark.extensions]
+    strikethrough = false
+    [goldmark.extensions.extras]
+      [goldmark.extensions.extras.delete]
+        enable = true
+      [goldmark.extensions.extras.subscript]
+        enable = true
+  [goldmark.renderer]
+    unsafe = true
 
-# use {.[css-class]} after a paragraph to apply styling
-[goldmark.parser]
-[goldmark.parser.attribute]
-  block = true
+  # use {.[css-class]} after a paragraph to apply styling
+  [goldmark.parser]
+  [goldmark.parser.attribute]
+    block = true
 
-# let the theme styling apply for code blocks
-[highlight]
-  noClasses = false
-
-[tableOfContents]
-  startLevel = 2
-  endLevel = 4
+  # let the theme styling apply for code blocks
+  [highlight]
+    noClasses = false
 
+  [tableOfContents]
+    startLevel = 2
+    endLevel = 4