fix: added zIndex varibale to HelpMark

Author: Полеводин Дмитрий Игоревич (4094029)

src/bundle/settings/index.tsx

@@ -26,6 +26,7 @@ import type {MarkdownEditorMode, MarkdownEditorSplitMode} from '../types';
 import {MarkdownHints} from './MarkdownHints';
 
 import './index.scss';
+import '../../styles/_zindex.scss';
 
 const placement: PopupPlacement = ['bottom-end', 'top-end'];
 
@@ -154,6 +155,7 @@ const SettingsContent: React.FC<SettingsContentProps> = function SettingsContent
                         popoverProps={{
                             placement: mdHelpPlacement,
                             modal: false,
+                            zIndex: 'var(--md-editor-sticky-toolbar-popup-z-index)',
                         }}
                         className={bContent('mode-help')}
                     >

src/styles/_zindex.scss

@@ -7,4 +7,10 @@ $z-index-map: (
     'table-view-button': 100,
     'table-cell-button': 110,
     'sticky-toolbar': 2000,
+    'sticky-toolbar-popup': 2100,
 );
+
+:root {
+    --md-editor-sticky-toolbar-popup-z-index: #{map-get($z-index-map, 'sticky-toolbar-popup')}
+}
+