diff --git a/MarkdownPreview.sublime-settings b/MarkdownPreview.sublime-settings
index 2435d01c..239989a8 100644
--- a/MarkdownPreview.sublime-settings
+++ b/MarkdownPreview.sublime-settings
@@ -72,12 +72,12 @@
         // You can't include "extra" and "superfences"
         // as "fenced_code" can not be included with "superfences",
         // so we include the pieces separately.
-        "markdown.extensions.smart_strong",
         "markdown.extensions.footnotes",
         "markdown.extensions.attr_list",
         "markdown.extensions.def_list",
         "markdown.extensions.tables",
         "markdown.extensions.abbr",
+        "pymdownx.betterem",
         {
             "markdown.extensions.codehilite": {
                 "guess_lang": false
@@ -101,7 +101,22 @@
         "markdown.extensions.admonition",
 
         // PyMdown extensions that help give a GitHub-ish feel
-        "pymdownx.superfences",  // Nested fences and UML support
+        {
+            "pymdownx.superfences": { // Nested fences and UML support
+                "custom_fences": [
+                    {
+                        "name": "flow",
+                        "class": "uml-flowchart",
+                        "format": {"!!python/name": "pymdownx.superfences.fence_code_format"}
+                    },
+                    {
+                        "name": "sequence",
+                        "class": "uml-sequence-diagram",
+                        "format": {"!!python/name": "pymdownx.superfences.fence_code_format"}
+                    }
+                ]
+            }
+        },
         {
             "pymdownx.magiclink": {   // Auto linkify URLs and email addresses
                 "repo_url_shortener": true,
diff --git a/docs/src/markdown/changes.md b/docs/src/markdown/changes.md
index f89873ef..9eaf4d17 100644
--- a/docs/src/markdown/changes.md
+++ b/docs/src/markdown/changes.md
@@ -1,5 +1,10 @@
 # Changes
 
+## 2.2.1
+
+- Add support for Markdown 3+ and Pymdownx 6+.
+- Add viewport scaling in HTML.
+
 ## 2.2.0
 
 - Add basic GitLab support.
diff --git a/examples/test.md b/examples/test.md
index 526975f0..5224705c 100644
--- a/examples/test.md
+++ b/examples/test.md
@@ -63,7 +63,14 @@
                 image_path: https://assets-cdn.github.com/images/icons/emoji/unicode/
                 non_standard_image_path: https://assets-cdn.github.com/images/icons/emoji/
           - pymdownx.tasklist
-          - pymdownx.superfences
+          - pymdownx.superfences:
+              custom_fences:
+                - name: flow
+                  class: uml-flowchart
+                  format: !!python/name:pymdownx.superfences.fence_code_format
+                - name: sequence
+                  class: uml-sequence-diagram
+                  format: !!python/name:pymdownx.superfences.fence_code_format
 ---
 test: This tests the meta extension
 title: This title will be overridden by YAML
diff --git a/markdown_wrapper.py b/markdown_wrapper.py
index 192c3160..61498141 100644
--- a/markdown_wrapper.py
+++ b/markdown_wrapper.py
@@ -1,7 +1,7 @@
 """Markdown Preview wrapper."""
 from __future__ import absolute_import
 import traceback
-from markdown import Markdown, util
+from markdown import Markdown, util, version_info
 from markdown.extensions import Extension
 
 
@@ -26,13 +26,17 @@ def registerExtensions(self, extensions, configs):  # noqa
         We are overriding this in order to gracefully handle bad extensions
         and to prevent old deprecated style of 'extensions(option=value)'.
         """
+        md3 = version_info[0] > 2
         for ext in extensions:
             try:
                 # Make sure we aren't using old form `extension(option=value)`
                 if isinstance(ext, util.string_type) and ('(' not in ext):
                     ext = self.build_extension(ext, configs.get(ext, []))
                 if isinstance(ext, Extension):
-                    ext.extendMarkdown(self, globals())
+                    if md3:
+                        ext._extendMarkdown(self)
+                    else:
+                        ext.extendMarkdown(self, globals())
                 elif ext is not None:
                     raise TypeError(
                         'Extension "%s.%s" must be of type: "markdown.Extension"'