fix: Menu SubMenu background in dark theme (#25205)

close #25202

components/menu/__tests__/__snapshots__/demo.test.js.snap

@@ -1156,7 +1156,7 @@ Array [
           Option 3
         </li>
         <li
-          class="ant-menu-item ant-menu-item-danger ant-menu-item-only-child"
+          class="ant-menu-item ant-menu-item-only-child"
           role="menuitem"
           style="padding-left:48px"
         >

components/menu/demo/horizontal.md

@@ -26,14 +26,13 @@ class App extends React.Component {
 
   handleClick = e => {
     console.log('click ', e);
-    this.setState({
-      current: e.key,
-    });
+    this.setState({ current: e.key });
   };
 
   render() {
+    const { current } = this.state;
     return (
-      <Menu onClick={this.handleClick} selectedKeys={[this.state.current]} mode="horizontal">
+      <Menu onClick={this.handleClick} selectedKeys={[current]} mode="horizontal">
         <Menu.Item key="mail" icon={<MailOutlined />}>
           Navigation One
         </Menu.Item>

components/menu/demo/theme.md

@@ -61,9 +61,7 @@ class Sider extends React.Component {
             <Menu.Item key="1">Option 1</Menu.Item>
             <Menu.Item key="2">Option 2</Menu.Item>
             <Menu.Item key="3">Option 3</Menu.Item>
-            <Menu.Item key="4" danger>
-              Option 4
-            </Menu.Item>
+            <Menu.Item key="4">Option 4</Menu.Item>
           </SubMenu>
           <SubMenu key="sub2" icon={<AppstoreOutlined />} title="Navigation Two">
             <Menu.Item key="5">Option 5</Menu.Item>

components/menu/style/dark.less

@@ -1,6 +1,7 @@
 .@{menu-prefix-cls} {
   // dark theme
   &&-dark,
+  &-dark &-sub,
   &&-dark &-sub {
     color: @menu-dark-color;
     background: @menu-dark-bg;