diff --git a/demos/src/Marks/Subscript/React/index.html b/demos/src/Marks/Subscript/React/index.html
new file mode 100644
index 00000000..1f43df8a
--- /dev/null
+++ b/demos/src/Marks/Subscript/React/index.html
@@ -0,0 +1,15 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+  </head>
+  <body>
+    <div id="app"></div>
+    <script type="module">
+      import setup from "../../../../setup/react.ts";
+      import source from "@source";
+      setup("Marks/Subscript", source);
+    </script>
+  </body>
+</html>
diff --git a/demos/src/Marks/Subscript/React/index.jsx b/demos/src/Marks/Subscript/React/index.jsx
new file mode 100644
index 00000000..557ff753
--- /dev/null
+++ b/demos/src/Marks/Subscript/React/index.jsx
@@ -0,0 +1,46 @@
+import React from 'react'
+import { useEditor, EditorContent } from '@tiptap/react'
+import Document from '@tiptap/extension-document'
+import Paragraph from '@tiptap/extension-paragraph'
+import Text from '@tiptap/extension-text'
+import Subscript from '@tiptap/extension-subscript'
+
+export default () => {
+  const editor = useEditor({
+    extensions: [Document, Paragraph, Text, Subscript],
+    content: `
+        <p>This is regular text.</p>
+        <p><sub>This is subscript.</sub></p>
+        <p><span style="vertical-align: sub">And this.</span></p>
+      `,
+  })
+
+  if (!editor) {
+    return null
+  }
+
+  return (
+    <>
+      <button
+        onClick={() => editor.chain().focus().toggleSubscript().run()}
+        className={editor.isActive('subscript') ? 'is-active' : ''}
+      >
+        toggleSubscript
+      </button>
+      <button
+        onClick={() => editor.chain().focus().setSubscript().run()}
+        disabled={editor.isActive('subscript')}
+      >
+        setSubscript
+      </button>
+      <button
+        onClick={() => editor.chain().focus().unsetSubscript().run()}
+        disabled={!editor.isActive('subscript')}
+      >
+        unsetSubscript
+      </button>
+
+      <EditorContent editor={editor} />
+    </>
+  )
+}
diff --git a/demos/src/Marks/Subscript/React/index.spec.js b/demos/src/Marks/Subscript/React/index.spec.js
new file mode 100644
index 00000000..7610ab9a
--- /dev/null
+++ b/demos/src/Marks/Subscript/React/index.spec.js
@@ -0,0 +1,39 @@
+context('/src/Marks/Subscript/React/', () => {
+  before(() => {
+    cy.visit('/src/Marks/Subscript/React/')
+  })
+
+  beforeEach(() => {
+    cy.get('.ProseMirror').then(([{ editor }]) => {
+      editor.commands.setContent('<p>Example Text</p>')
+      cy.get('.ProseMirror').type('{selectall}')
+    })
+  })
+
+  it('should transform inline style to sub tags', () => {
+    cy.get('.ProseMirror').then(([{ editor }]) => {
+      editor.commands.setContent('<p><span style="vertical-align: sub">Example Text</span></p>')
+      expect(editor.getHTML()).to.eq('<p><sub>Example Text</sub></p>')
+    })
+  })
+
+  it('sould omit inline style with a different vertical align', () => {
+    cy.get('.ProseMirror').then(([{ editor }]) => {
+      editor.commands.setContent('<p><b style="vertical-align: middle">Example Text</b></p>')
+      expect(editor.getHTML()).to.eq('<p>Example Text</p>')
+    })
+  })
+
+  it('the button should make the selected text bold', () => {
+    cy.get('button:first').click()
+
+    cy.get('.ProseMirror').find('sub').should('contain', 'Example Text')
+  })
+
+  it('the button should toggle the selected text bold', () => {
+    cy.get('button:first').click()
+    cy.get('.ProseMirror').type('{selectall}')
+    cy.get('button:first').click()
+    cy.get('.ProseMirror sub').should('not.exist')
+  })
+})
