diff --git a/frontend/src/components/Header.tsx b/frontend/src/components/Header.tsx
index 7549f61..443927d 100644
--- a/frontend/src/components/Header.tsx
+++ b/frontend/src/components/Header.tsx
@@ -1,16 +1,31 @@
 import React from 'react';
 import { Layout, Button, Space, Tag, Dropdown } from 'antd';
-import { MenuFoldOutlined, MenuUnfoldOutlined, UserOutlined, GlobalOutlined, BgColorsOutlined } from '@ant-design/icons';
+import {
+  MenuFoldOutlined,
+  MenuUnfoldOutlined,
+  MenuOutlined,
+  UserOutlined,
+  GlobalOutlined,
+  BgColorsOutlined,
+} from '@ant-design/icons';
 import { useAuthStore } from '../stores/authStore';
 import { useThemeStore, ThemeMode } from '../stores/themeStore';
 import { useI18n } from '../i18n';
+import useIsMobile from '../hooks/useIsMobile';
 
 const { Header } = Layout;
 
-const HeaderBar: React.FC<{ collapsed: boolean; setCollapsed: (v: boolean) => void; }> = ({ collapsed, setCollapsed }) => {
+type Props = {
+  collapsed: boolean;
+  setCollapsed: (v: boolean) => void;
+  onOpenMobileNav?: () => void;
+};
+
+const HeaderBar: React.FC<Props> = ({ collapsed, setCollapsed, onOpenMobileNav }) => {
   const { t, locale, setLocale } = useI18n();
   const { mode, setMode } = useThemeStore();
   const username = useAuthStore((s) => s.username);
+  const isMobile = useIsMobile();
 
   const langItems = [
     { key: 'zh', label: '中文' },
@@ -23,17 +38,58 @@ const HeaderBar: React.FC<{ collapsed: boolean; setCollapsed: (v: boolean) => vo
     { key: 'system', label: t('settings.system') },
   ];
 
+  const displayName = username || 'Admin';
+  const shortName = displayName.length > 8 ? `${displayName.slice(0, 8)}…` : displayName;
+
   return (
-    <Header style={{ padding: '0 24px', background: 'transparent', display: 'flex', alignItems: 'center', justifyContent: 'space-between' }}>
-      <Button type="text" icon={collapsed ? <MenuUnfoldOutlined /> : <MenuFoldOutlined />} onClick={() => setCollapsed(!collapsed)} />
-      <Space>
-        <Dropdown menu={{ items: themeItems, selectedKeys: [mode], onClick: (e) => setMode(e.key as ThemeMode) }}>
-          <Button type="text" icon={<BgColorsOutlined />}>{t('settings.theme')}</Button>
+    <Header
+      style={{
+        padding: isMobile ? '0 12px' : '0 24px',
+        background: 'transparent',
+        display: 'flex',
+        alignItems: 'center',
+        justifyContent: 'space-between',
+        gap: 8,
+        height: 64,
+        lineHeight: '64px',
+      }}
+    >
+      {isMobile ? (
+        <Button type="text" icon={<MenuOutlined />} onClick={onOpenMobileNav} aria-label="menu" />
+      ) : (
+        <Button
+          type="text"
+          icon={collapsed ? <MenuUnfoldOutlined /> : <MenuFoldOutlined />}
+          onClick={() => setCollapsed(!collapsed)}
+        />
+      )}
+
+      <Space size={isMobile ? 4 : 'middle'} wrap>
+        <Dropdown
+          menu={{
+            items: themeItems,
+            selectedKeys: [mode],
+            onClick: (e) => setMode(e.key as ThemeMode),
+          }}
+        >
+          <Button type="text" icon={<BgColorsOutlined />}>
+            {!isMobile && t('settings.theme')}
+          </Button>
         </Dropdown>
-        <Dropdown menu={{ items: langItems, selectedKeys: [locale], onClick: (e) => setLocale(e.key as 'en' | 'zh') }}>
-          <Button type="text" icon={<GlobalOutlined />}>{locale === 'zh' ? '中文' : 'English'}</Button>
+        <Dropdown
+          menu={{
+            items: langItems,
+            selectedKeys: [locale],
+            onClick: (e) => setLocale(e.key as 'en' | 'zh'),
+          }}
+        >
+          <Button type="text" icon={<GlobalOutlined />}>
+            {!isMobile && (locale === 'zh' ? '中文' : 'English')}
+          </Button>
         </Dropdown>
-        <Tag icon={<UserOutlined />}>{username || 'Admin'}</Tag>
+        <Tag icon={<UserOutlined />} style={{ marginInlineEnd: 0 }}>
+          {isMobile ? shortName : displayName}
+        </Tag>
       </Space>
     </Header>
   );
diff --git a/frontend/src/components/Sidebar.tsx b/frontend/src/components/Sidebar.tsx
index f2534ac..d571d4a 100644
--- a/frontend/src/components/Sidebar.tsx
+++ b/frontend/src/components/Sidebar.tsx
@@ -10,7 +10,7 @@ import { useI18n } from '../i18n';
 
 const { Sider } = Layout;
 
-const Sidebar: React.FC<{ collapsed: boolean }> = ({ collapsed }) => {
+export function useSidebarMenuItems(onNavigate?: () => void) {
   const navigate = useNavigate();
   const location = useLocation();
   const logout = useAuthStore((s) => s.logout);
@@ -26,15 +26,86 @@ const Sidebar: React.FC<{ collapsed: boolean }> = ({ collapsed }) => {
     { key: '/settings', icon: <SettingOutlined />, label: t('nav.settings') },
   ];
 
+  const onMenuClick = ({ key }: { key: string }) => {
+    navigate(key);
+    onNavigate?.();
+  };
+
+  const onLogout = () => {
+    logout();
+    navigate('/login');
+    onNavigate?.();
+  };
+
+  return { items, selectedKeys: [location.pathname], onMenuClick, onLogout, t };
+}
+
+/** Shared nav body used by desktop Sider and mobile Drawer. */
+export const SidebarMenu: React.FC<{ onNavigate?: () => void; style?: React.CSSProperties }> = ({
+  onNavigate,
+  style,
+}) => {
+  const { items, selectedKeys, onMenuClick, onLogout, t } = useSidebarMenuItems(onNavigate);
+
   return (
-    <Sider trigger={null} collapsible collapsed={collapsed} theme="light">
-      <div style={{ height: 64, display: 'flex', alignItems: 'center', justifyContent: 'center', fontWeight: 700, fontSize: 18 }}>
+    <div style={{ display: 'flex', flexDirection: 'column', height: '100%', ...style }}>
+      <div
+        style={{
+          height: 64,
+          display: 'flex',
+          alignItems: 'center',
+          justifyContent: 'center',
+          fontWeight: 700,
+          fontSize: 18,
+          flexShrink: 0,
+        }}
+      >
         3M-UI
       </div>
-      <Menu mode="inline" selectedKeys={[location.pathname]} items={items} onClick={({ key }) => navigate(key)} />
-      <Menu mode="inline" selectable={false} items={[
-        { key: 'logout', icon: <LogoutOutlined />, label: t('nav.logout'), onClick: () => { logout(); navigate('/login'); } },
-      ]} style={{ position: 'absolute', bottom: 0, width: '100%' }} />
+      <Menu
+        mode="inline"
+        selectedKeys={selectedKeys}
+        items={items}
+        onClick={onMenuClick}
+        style={{ flex: 1, borderInlineEnd: 'none' }}
+      />
+      <Menu
+        mode="inline"
+        selectable={false}
+        items={[
+          {
+            key: 'logout',
+            icon: <LogoutOutlined />,
+            label: t('nav.logout'),
+            onClick: onLogout,
+          },
+        ]}
+        style={{ borderInlineEnd: 'none', borderTop: '1px solid rgba(5,5,5,0.06)' }}
+      />
+    </div>
+  );
+};
+
+const Sidebar: React.FC<{ collapsed: boolean }> = ({ collapsed }) => {
+  return (
+    <Sider
+      trigger={null}
+      collapsible
+      collapsed={collapsed}
+      theme="light"
+      breakpoint="md"
+      collapsedWidth={80}
+      width={220}
+      style={{
+        overflow: 'auto',
+        height: '100vh',
+        position: 'sticky',
+        insetInlineStart: 0,
+        top: 0,
+        bottom: 0,
+      }}
+    >
+      <SidebarMenu />
     </Sider>
   );
 };