fix(css): fill mobile safe-area zones with background color

Use fixed ::before and ::after pseudo-elements to render the
background color in safe-area inset zones, preventing transparent
gaps on notched mobile devices while maintaining body padding for
content flow.

src/components/ThemeToggle.tsx

@@ -0,0 +1,27 @@
+import { MoonIcon, SunIcon, MonitorIcon } from "lucide-react"
+import { Button } from "@/components/ui/button"
+import { useThemeStore, type ThemeMode } from "@/store/themeStore"
+import { usePlatform } from "@/hooks/usePlatform"
+
+const next: Record<ThemeMode, ThemeMode> = { system: "dark", dark: "light", light: "system" }
+const icon: Record<ThemeMode, typeof SunIcon> = { system: MonitorIcon, dark: MoonIcon, light: SunIcon }
+
+export default function ThemeToggle() {
+  const mode = useThemeStore((s) => s.mode)
+  const setMode = useThemeStore((s) => s.setMode)
+  const platform = usePlatform()
+  const hideTitle = platform === "mobile"
+
+  const Icon = icon[mode]
+
+  return (
+    <Button
+      variant="ghost"
+      size="icon-sm"
+      onClick={() => setMode(next[mode])}
+      {...(!hideTitle && { title: `主题：${mode === "system" ? "跟随系统" : mode === "dark" ? "深色" : "浅色"}` })}
+    >
+      <Icon className="size-4" />
+    </Button>
+  )
+}

src/components/layout/AdminLayout.tsx

@@ -1,6 +1,7 @@
 import { NavLink, Outlet, useNavigate } from "react-router-dom"
 import { BookOpenIcon, ListIcon, LogOutIcon } from "lucide-react"
 import { Button } from "@/components/ui/button"
+import ThemeToggle from "@/components/ThemeToggle"
 import { useAuthStore } from "@/store/authStore"
 import { usePlatform } from "@/hooks/usePlatform"
 import { useIsMobile } from "@/hooks/useIsMobile"
@@ -45,6 +46,7 @@ export default function AdminLayout() {
           </nav>
           <div className="flex items-center gap-2 border-t px-4 py-3">
             <span className="min-w-0 flex-1 truncate text-sm text-muted-foreground">{username}</span>
+            <ThemeToggle />
             <Button variant="ghost" size="icon-sm" onClick={handleLogout} {...(!hideTitle && { title: "退出" })}>
               <LogOutIcon className="size-4" />
             </Button>
@@ -63,6 +65,7 @@ export default function AdminLayout() {
         <span className="font-heading text-sm font-semibold">管理后台</span>
         <div className="flex items-center gap-2">
           <span className="text-sm text-muted-foreground">{username}</span>
+          <ThemeToggle />
           <Button variant="ghost" size="icon-sm" onClick={handleLogout}>
             <LogOutIcon className="size-4" />
           </Button>

src/components/layout/AppLayout.tsx

@@ -1,6 +1,7 @@
 import { Link, Outlet, useNavigate } from "react-router-dom"
 import { useAuthStore } from "@/store/authStore"
 import { Button } from "@/components/ui/button"
+import ThemeToggle from "@/components/ThemeToggle"
 
 export default function AppLayout() {
   const token = useAuthStore((s) => s.token)
@@ -31,6 +32,7 @@ export default function AppLayout() {
             )}
           </nav>
           <div className="ml-auto flex items-center gap-3">
+            <ThemeToggle />
             {token ? (
               <>
                 <span className="text-sm text-muted-foreground">{username}</span>

src/components/layout/UserLayout.tsx

@@ -0,0 +1,109 @@
+import { NavLink, Outlet, useNavigate } from "react-router-dom"
+import { BookOpenIcon, BookMarkedIcon, LogOutIcon } from "lucide-react"
+import { Button } from "@/components/ui/button"
+import ThemeToggle from "@/components/ThemeToggle"
+import { useAuthStore } from "@/store/authStore"
+import { usePlatform } from "@/hooks/usePlatform"
+import { useIsMobile } from "@/hooks/useIsMobile"
+
+const navItems = [
+  { to: "/books", label: "书目", icon: BookOpenIcon },
+  { to: "/my-borrows", label: "我的借阅", icon: BookMarkedIcon },
+]
+
+export default function UserLayout() {
+  const username = useAuthStore((s) => s.username)
+  const token = useAuthStore((s) => s.token)
+  const clearAuth = useAuthStore((s) => s.clearAuth)
+  const navigate = useNavigate()
+  const platform = usePlatform()
+  const isMobile = useIsMobile()
+  const hideTitle = platform === "mobile"
+
+  function handleLogout() {
+    clearAuth()
+    navigate("/books", { replace: true })
+  }
+
+  const linkClass = ({ isActive }: { isActive: boolean }) =>
+    `flex items-center gap-2 rounded-lg px-3 py-2 text-sm font-medium transition-colors ${
+      isActive ? "bg-primary text-primary-foreground" : "text-muted-foreground hover:bg-muted hover:text-foreground"
+    }`
+
+  if (!isMobile) {
+    return (
+      <div className="flex min-h-screen">
+        <aside className="fixed top-0 left-0 z-50 flex h-full w-56 flex-col border-r bg-background">
+          <div className="flex h-12 items-center gap-2 border-b px-4">
+            <span className="font-heading text-base font-semibold">图书管理系统</span>
+          </div>
+          <nav className="flex-1 space-y-1 p-3">
+            {navItems.map(({ to, label, icon: Icon }) => (
+              <NavLink key={to} to={to} className={linkClass} end>
+                <Icon className="size-4" />
+                {label}
+              </NavLink>
+            ))}
+          </nav>
+          <div className="flex items-center gap-2 border-t px-4 py-3">
+            {token ? (
+              <>
+                <span className="min-w-0 flex-1 truncate text-sm text-muted-foreground">{username}</span>
+                <Button variant="ghost" size="icon-sm" onClick={handleLogout} {...(!hideTitle && { title: "退出" })}>
+                  <LogOutIcon className="size-4" />
+                </Button>
+              </>
+            ) : (
+              <>
+                <span className="min-w-0 flex-1 truncate text-sm text-muted-foreground">未登录</span>
+                <Button variant="ghost" size="sm" onClick={() => navigate("/login")}>
+                  登录
+                </Button>
+              </>
+            )}
+          </div>
+        </aside>
+        <main className="ml-56 flex-1 px-6 py-6">
+          <div className="mb-4 flex justify-end">
+            <ThemeToggle />
+          </div>
+          <Outlet />
+        </main>
+      </div>
+    )
+  }
+
+  return (
+    <div className="flex min-h-screen flex-col">
+      <header className="sticky top-[var(--safe-top,0px)] z-40 flex h-12 items-center justify-between border-b bg-background px-4">
+        <span className="font-heading text-sm font-semibold">图书管理系统</span>
+        <div className="flex items-center gap-2">
+          <ThemeToggle />
+          {token ? (
+            <>
+              <span className="text-sm text-muted-foreground">{username}</span>
+              <Button variant="ghost" size="icon-sm" onClick={handleLogout}>
+                <LogOutIcon className="size-4" />
+              </Button>
+            </>
+          ) : (
+            <Button variant="ghost" size="sm" onClick={() => navigate("/login")}>
+              登录
+            </Button>
+          )}
+        </div>
+      </header>
+      <main className="flex-1 px-4 py-4">
+        <Outlet />
+      </main>
+      <nav className="sticky bottom-[var(--safe-bottom,0px)] z-40 flex border-t bg-background">
+        {navItems.map(({ to, label, icon: Icon }) => (
+          <NavLink key={to} to={to} className={linkClass + " flex-1 justify-center py-3"} end>
+            <Icon className="size-4" />
+            <span className="text-xs">{label}</span>
+          </NavLink>
+        ))}
+      </nav>
+    </div>
+  )
+}

src/main.tsx

@@ -5,6 +5,7 @@ import { QueryClient, QueryClientProvider } from "@tanstack/react-query"
 import { Toaster } from "@/components/ui/sonner"
 import { PlatformProvider } from "@/hooks/usePlatform"
 import { MobileClass } from "@/hooks/useIsMobile"
+import { ThemeProvider } from "@/store/themeStore"
 import { router } from "@/router"
 import "./index.css"
 
@@ -13,6 +14,7 @@ const queryClient = new QueryClient()
 ReactDOM.createRoot(document.getElementById("root") as HTMLElement).render(
   <React.StrictMode>
     <QueryClientProvider client={queryClient}>
+      <ThemeProvider />
       <MobileClass />
       <PlatformProvider>
         <RouterProvider router={router} />

src/router/index.tsx

@@ -7,6 +7,7 @@ import MyBorrowsPage from "@/features/borrows/MyBorrowsPage"
 import AdminBooksPage from "@/features/admin/AdminBooksPage"
 import AdminBorrowsPage from "@/features/admin/AdminBorrowsPage"
 import AppLayout from "@/components/layout/AppLayout"
+import UserLayout from "@/components/layout/UserLayout"
 import AdminLayout from "@/components/layout/AdminLayout"
 
 function RootRedirect() {
@@ -26,6 +27,11 @@ export const router = createBrowserRouter([
         path: "/",
         element: <RootRedirect />,
       },
+    ],
+  },
+  {
+    element: <UserLayout />,
+    children: [
       {
         path: "/books",
         element: <BooksPage />,

src/store/themeStore.ts

@@ -0,0 +1,64 @@
+import { create } from "zustand"
+import { useEffect } from "react"
+
+export type ThemeMode = "system" | "light" | "dark"
+
+interface ThemeState {
+  mode: ThemeMode
+  setMode: (mode: ThemeMode) => void
+}
+
+function loadTheme(): ThemeMode {
+  try {
+    const v = localStorage.getItem("theme")
+    if (v === "light" || v === "dark" || v === "system") return v
+  } catch { /* unavailable */ }
+  return "system"
+}
+
+function systemIsDark(): boolean {
+  return window.matchMedia("(prefers-color-scheme: dark)").matches
+}
+
+export function effectiveTheme(mode: ThemeMode): "light" | "dark" {
+  if (mode === "system") return systemIsDark() ? "dark" : "light"
+  return mode
+}
+
+function applyTheme(mode: ThemeMode) {
+  const root = document.documentElement
+  if (effectiveTheme(mode) === "dark") {
+    root.classList.add("dark")
+  } else {
+    root.classList.remove("dark")
+  }
+}
+
+export const useThemeStore = create<ThemeState>((set) => ({
+  mode: loadTheme(),
+  setMode: (mode) => {
+    localStorage.setItem("theme", mode)
+    applyTheme(mode)
+    set({ mode })
+  },
+}))
+
+export function ThemeProvider() {
+  const mode = useThemeStore((s) => s.mode)
+
+  useEffect(() => {
+    applyTheme(mode)
+  }, [mode])
+
+  useEffect(() => {
+    if (mode !== "system") return
+    const mql = window.matchMedia("(prefers-color-scheme: dark)")
+    function sync() {
+      applyTheme("system")
+    }
+    mql.addEventListener("change", sync)
+    return () => mql.removeEventListener("change", sync)
+  }, [mode])
+
+  return null
+}