diff --git a/components/dropdown/demo/menu-full.md b/components/dropdown/demo/menu-full.md
index 5681b2623908..5ab901ddb83f 100644
--- a/components/dropdown/demo/menu-full.md
+++ b/components/dropdown/demo/menu-full.md
@@ -8,11 +8,15 @@ debug: true
 
 ## zh-CN
 
-此演示需要注意查看 Dropdown 内 Menu 的样式是否正常。[#19150](https://github.com/ant-design/ant-design/pull/19150)
+此演示需要注意去掉 Reset 样式后查看 Dropdown 内 Menu 的样式是否正常。
+
+[#19150](https://github.com/ant-design/ant-design/pull/19150)
 
 ## en-US
 
-This demo was created for debugging Menu styles inside Dropdown. [#19150](https://github.com/ant-design/ant-design/pull/19150)
+This demo was created for debugging Menu styles inside Dropdown.
+
+[#19150](https://github.com/ant-design/ant-design/pull/19150)
 
 ```jsx
 import { Menu, Dropdown, Icon } from 'antd';
@@ -21,6 +25,10 @@ const { SubMenu } = Menu;
 
 const menu = (
   <Menu selectedKeys={['1']} openKeys={['sub1']}>
+    <Menu.ItemGroup key="group" title="Item Group">
+      <Menu.Item key="01">Option 0</Menu.Item>
+      <Menu.Item key="02">Option 0</Menu.Item>
+    </Menu.ItemGroup>
     <SubMenu
       key="sub1"
       title={
diff --git a/components/dropdown/style/index.less b/components/dropdown/style/index.less
index 0ca291882940..5d48f1c678a7 100644
--- a/components/dropdown/style/index.less
+++ b/components/dropdown/style/index.less
@@ -81,6 +81,7 @@
       ul {
         margin-right: 0.3em;
         margin-left: 0.3em;
+        padding: 0;
       }
     }
 
@@ -139,6 +140,7 @@
         line-height: 0;
         background-color: @border-color-split;
       }
+
       .@{dropdown-prefix-cls}-menu-submenu-arrow {
         position: absolute;
         right: @padding-xs;
@@ -150,6 +152,12 @@
       }
     }
 
+    &-item-group-list {
+      margin: 0 8px;
+      padding: 0;
+      list-style: none;
+    }
+
     &-submenu-title {
       padding-right: 26px;
     }
diff --git a/site/theme/static/demo.less b/site/theme/static/demo.less
index 6d86a40c796f..fd7c9145c253 100644
--- a/site/theme/static/demo.less
+++ b/site/theme/static/demo.less
@@ -89,7 +89,6 @@
 
     h4,
     section& p {
-      width: 98%;
       margin: 0;
     }