refactor: give playground a custom theme to satisfy tests

demos/playground/src/RichTextComposer.svelte

@@ -46,7 +46,7 @@
   } from 'svelte-lexical';
   import {prepopulatedRichText} from './prepopulatedRichText';
   import type {SettingsStore} from './settings/setttingsStore';
-  import {editorTheme as PlaygroundEditorTheme} from 'svelte-lexical';
+  import PlaygroundEditorTheme from './themes/PlaygroundEditorTheme';
   import ToolbarPlayground from './ToolbarPlayground.svelte';
   import {createWebsocketProvider} from './collaboration';
 

demos/playground/src/index.css

@@ -1738,22 +1738,6 @@ button.item.dropdown-item-active i {
   z-index: 3;
 }
 
-.PlaygroundEditorTheme__blockCursor {
-  display: block;
-  pointer-events: none;
-  position: absolute;
-}
-
-.PlaygroundEditorTheme__blockCursor:after {
-  content: '';
-  display: block;
-  position: absolute;
-  top: -2px;
-  width: 20px;
-  border-top: 1px solid black;
-  animation: CursorBlink 1.1s steps(2, start) infinite;
-}
-
 @keyframes CursorBlink {
   to {
     visibility: hidden;

demos/playground/src/themes/CommentEditorTheme.css

@@ -0,0 +1,13 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ *
+ */
+
+.CommentEditorTheme__paragraph {
+  margin: 0;
+  position: 'relative';
+}

demos/playground/src/themes/CommentEditorTheme.ts

@@ -0,0 +1,20 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ */
+
+import type {EditorThemeClasses} from 'svelte-lexical';
+
+import './CommentEditorTheme.css';
+
+import baseTheme from './PlaygroundEditorTheme';
+
+const theme: EditorThemeClasses = {
+  ...baseTheme,
+  paragraph: 'CommentEditorTheme__paragraph',
+};
+
+export default theme;