diff --git a/packages/core/scripts/generate-site.mjs b/packages/core/scripts/generate-site.mjs
index bf21b6a..042fed9 100644
--- a/packages/core/scripts/generate-site.mjs
+++ b/packages/core/scripts/generate-site.mjs
@@ -23,6 +23,7 @@ const SITES_ROOT = path.join(REPO_ROOT, "sites");
 // ====================================================================
 const SITES = {
   "ai-stack": {
+    themeId: "ai-stack",
     authVariant: "glass",
     themeClass: "site-ai-stack",
     brandZh: {
@@ -93,6 +94,7 @@ const SITES = {
     },
   },
   launchai: {
+    themeId: "launchai",
     authVariant: "gradient",
     themeClass: "site-launchai",
     brandZh: {
@@ -161,6 +163,7 @@ const SITES = {
     },
   },
   "the-ai-ledger": {
+    themeId: "the-ai-ledger",
     authVariant: "editorial",
     themeClass: "site-the-ai-ledger",
     brandZh: {
@@ -230,6 +233,7 @@ const SITES = {
     },
   },
   "devai-tools": {
+    themeId: "devai-tools",
     authVariant: "terminal",
     themeClass: "site-devai-tools",
     brandZh: {
@@ -297,6 +301,7 @@ const SITES = {
     },
   },
   findai: {
+    themeId: "findai",
     authVariant: "minimal",
     themeClass: "site-findai",
     brandZh: {
@@ -782,6 +787,9 @@ NEXT_PUBLIC_APP_NAME="${site.brand.name}"
 # 登录页品牌模板（分栏侧栏颜色与标语）
 NEXT_PUBLIC_AUTH_ACCENT="${site.accent}"
 NEXT_PUBLIC_AUTH_VARIANT="${site.authVariant}"
+# 站点主题标识（<html data-theme>）与默认深浅（light | dark，用户可切换）
+NEXT_PUBLIC_THEME_ID="${site.themeId}"
+NEXT_PUBLIC_DEFAULT_THEME="${site.defaultTheme}"
 NEXT_PUBLIC_AUTH_BRAND_TAGLINE="${site.brand.tagline}"
 # 开发阶段免邮箱验证（生产置 false 发送真实验证邮件）
 DEV_SKIP_EMAIL_VERIFY="true"
diff --git a/packages/core/src/components/ui/form.tsx b/packages/core/src/components/ui/form.tsx
index 8b04d66..cbca437 100644
--- a/packages/core/src/components/ui/form.tsx
+++ b/packages/core/src/components/ui/form.tsx
@@ -94,7 +94,7 @@ const FormLabel = React.forwardRef<
     <Label
       ref={ref}
       className={cn(
-        "text-[#9393A3] pb-0 text-sm",
+        "text-muted-foreground pb-0 text-sm",
         error && "text-destructive",
         className
       )}
diff --git a/packages/core/src/features/auth/components/social-auth-buttons.tsx b/packages/core/src/features/auth/components/social-auth-buttons.tsx
index 7b89530..8403d64 100644
--- a/packages/core/src/features/auth/components/social-auth-buttons.tsx
+++ b/packages/core/src/features/auth/components/social-auth-buttons.tsx
@@ -61,7 +61,7 @@ export function SocialAuthButtons({
   const loading = isLoading || mockLoading !== null;
 
   const btnClass =
-    "flex w-full items-center justify-center gap-2.5 rounded-lg border border-border bg-background px-4 py-2.5 text-[0.95rem] font-medium text-foreground transition-colors hover:bg-secondary/60 disabled:opacity-50";
+    "flex w-full items-center justify-center gap-2.5 rounded-lg border border-border bg-transparent px-4 py-2.5 text-[0.95rem] font-medium text-foreground transition-colors hover:bg-secondary/60 disabled:opacity-50";
 
   return (
     <div className="flex w-full flex-col gap-2.5">
diff --git a/packages/core/src/features/forms/components/form-shell.tsx b/packages/core/src/features/forms/components/form-shell.tsx
index 12a5f97..00cb6b7 100644
--- a/packages/core/src/features/forms/components/form-shell.tsx
+++ b/packages/core/src/features/forms/components/form-shell.tsx
@@ -85,7 +85,7 @@ export function FormShell<TFieldValues extends FieldValues>({
   if (variant === "glass") {
     return (
       <Form {...form}>
-        <div className="relative flex min-h-screen w-full items-center justify-center overflow-hidden bg-[linear-gradient(160deg,hsl(224_60%_12%),hsl(224_55%_22%)_60%,hsl(210_45%_30%))] px-4 py-12">
+        <div className="dark relative flex min-h-screen w-full items-center justify-center overflow-hidden bg-[linear-gradient(160deg,hsl(224_60%_12%),hsl(224_55%_22%)_60%,hsl(210_45%_30%))] px-4 py-12">
           <div className="pointer-events-none absolute -left-40 -top-40 h-96 w-96 rounded-full bg-blue-400/10 blur-3xl" />
           <div className="pointer-events-none absolute -bottom-40 -right-40 h-96 w-96 rounded-full bg-indigo-400/10 blur-3xl" />
           <div className="relative w-full max-w-md rounded-2xl border border-white/15 bg-white/[0.08] p-8 shadow-2xl backdrop-blur-xl sm:p-10">
@@ -118,7 +118,7 @@ export function FormShell<TFieldValues extends FieldValues>({
           className="relative flex min-h-screen w-full items-center justify-center px-4 py-12"
           style={{ background: `linear-gradient(140deg, hsl(${accent}) 0%, hsl(28 90% 55%) 100%)` }}
         >
-          <div className="w-full max-w-md rounded-3xl bg-white p-8 shadow-[0_24px_70px_rgba(0,0,0,0.25)] sm:p-10">
+          <div className="w-full max-w-md rounded-3xl bg-card p-8 shadow-[0_24px_70px_rgba(0,0,0,0.25)] sm:p-10">
             <div className="mb-7 flex items-center gap-2.5">
               <span
                 className="flex h-10 w-10 items-center justify-center rounded-2xl text-lg font-bold text-white"
@@ -134,7 +134,7 @@ export function FormShell<TFieldValues extends FieldValues>({
               {socialSlot}
               {children}
               {errorBox}
-              {submitBtn(`w-full rounded-2xl py-3.5 text-base font-bold text-white transition hover:opacity-90 disabled:opacity-60`)}
+              {submitBtn("w-full rounded-2xl bg-primary py-3.5 text-base font-bold text-primary-foreground transition hover:opacity-90 disabled:opacity-60")}
             </form>
             {footerNode}
           </div>
@@ -146,18 +146,18 @@ export function FormShell<TFieldValues extends FieldValues>({
   /* ================= 3. The AI Ledger：报纸头版 + 下划线输入 ================= */
   if (variant === "editorial") {
     const lineInput =
-      "w-full border-0 border-b-2 border-neutral-300 bg-transparent px-0 py-2 text-lg font-serif text-neutral-900 placeholder:text-neutral-400 focus:border-neutral-900 focus:outline-none rounded-none";
+      "auth-input w-full border-0 border-b-2 bg-transparent px-0 py-2 text-lg font-serif text-foreground placeholder:text-muted-foreground focus:outline-none rounded-none";
     return (
       <Form {...form}>
-        <div className="min-h-screen w-full bg-[hsl(42_45%_97%)] px-4 py-10 font-serif text-neutral-900">
+        <div className="min-h-screen w-full bg-background px-4 py-10 text-foreground">
           <div className="mx-auto max-w-xl">
             {/* 报头 */}
-            <div className="border-y-[3px] border-double border-neutral-900 py-3 text-center">
-              <p className="text-[10px] uppercase tracking-[0.35em] text-neutral-500">
+            <div className="border-y-[3px] border-double border-foreground py-3 text-center">
+              <p className="text-[10px] uppercase tracking-[0.35em] text-muted-foreground">
                 {new Date().toLocaleDateString("en-US", { weekday: "long", month: "long", day: "numeric", year: "numeric" })}
               </p>
               <h1 className="mt-1 text-4xl font-black tracking-tight">{brand}</h1>
-              <p className="mt-1 text-[10px] uppercase tracking-[0.35em] text-neutral-500">{tagline}</p>
+              <p className="mt-1 text-[10px] uppercase tracking-[0.35em] text-muted-foreground">{tagline}</p>
             </div>
 
             <h2 className="mt-10 text-center text-2xl font-bold">{title}</h2>
@@ -165,11 +165,11 @@ export function FormShell<TFieldValues extends FieldValues>({
               {socialSlot}
               {children}
               {errorBox}
-              {submitBtn("w-full border-2 border-neutral-900 bg-neutral-900 py-3 text-sm font-bold uppercase tracking-[0.2em] text-white transition hover:bg-transparent hover:text-neutral-900 disabled:opacity-60")}
+              {submitBtn("w-full border-2 border-foreground bg-foreground py-3 text-sm font-bold uppercase tracking-[0.2em] text-background transition hover:bg-transparent hover:text-foreground disabled:opacity-60")}
             </form>
             {footerNode}
           </div>
-          <div className="mx-auto mt-12 max-w-xl border-t border-neutral-300 pt-4 text-center text-[10px] uppercase tracking-[0.3em] text-neutral-400">
+          <div className="mx-auto mt-12 max-w-xl border-t border-border pt-4 text-center text-[10px] uppercase tracking-[0.3em] text-muted-foreground">
             © {new Date().getFullYear()} {brand}
           </div>
         </div>
@@ -180,28 +180,27 @@ export function FormShell<TFieldValues extends FieldValues>({
   /* ================= 4. DevAI.tools：深色终端窗口 ================= */
   if (variant === "terminal") {
     const termInput =
-      "w-full rounded border border-emerald-500/30 bg-black/50 px-3 py-2.5 font-mono text-sm text-emerald-100 placeholder:text-emerald-100/30 focus:border-emerald-400/70 focus:outline-none rounded-md";
-    const termLabel = "mb-1 block font-mono text-xs text-emerald-500/80";
+      "auth-input w-full rounded-md border border-border bg-card px-3 py-2.5 font-mono text-sm text-foreground placeholder:text-muted-foreground focus:border-primary/70 focus:outline-none";
     return (
       <Form {...form}>
-        <div className="flex min-h-screen w-full items-center justify-center bg-[hsl(220_25%_7%)] px-4 py-12">
-          <div className="w-full max-w-lg overflow-hidden rounded-lg border border-emerald-500/20 bg-[hsl(220_25%_9%)] shadow-[0_0_40px_rgba(16,185,129,0.06)]">
+        <div className="flex min-h-screen w-full items-center justify-center bg-background px-4 py-12">
+          <div className="w-full max-w-lg overflow-hidden rounded-lg border border-primary/20 bg-card shadow-[0_0_40px_rgba(16,185,129,0.06)]">
             {/* 终端标题栏 */}
-            <div className="flex items-center gap-2 border-b border-emerald-500/15 bg-black/40 px-4 py-3">
+            <div className="flex items-center gap-2 border-b border-border bg-secondary/60 px-4 py-3">
               <span className="h-3 w-3 rounded-full bg-red-500/80" />
               <span className="h-3 w-3 rounded-full bg-yellow-500/80" />
               <span className="h-3 w-3 rounded-full bg-emerald-500/80" />
-              <span className="ml-3 font-mono text-xs text-emerald-100/50">{brand.toLowerCase()} — auth</span>
+              <span className="ml-3 font-mono text-xs text-muted-foreground">{brand.toLowerCase()} — auth</span>
             </div>
             <div className="p-7">
-              <p className="font-mono text-sm text-emerald-400/90">
-                <span className="text-emerald-600">$</span> {brand.toLowerCase()} auth --login
+              <p className="font-mono text-sm text-primary/90">
+                <span className="text-primary/50">$</span> {brand.toLowerCase()} auth --login
               </p>
               <form onSubmit={form.handleSubmit(onSubmit)} className="mt-6 space-y-5">
                 {socialSlot}
                 {children}
                 {errorBox}
-                {submitBtn("w-full rounded-md bg-emerald-500 py-3 font-mono text-sm font-bold text-black transition hover:bg-emerald-400 disabled:opacity-60")}
+                {submitBtn("w-full rounded-md bg-primary py-3 font-mono text-sm font-bold text-primary-foreground transition hover:opacity-90 disabled:opacity-60")}
               </form>
               {footerNode}
             </div>
@@ -214,25 +213,25 @@ export function FormShell<TFieldValues extends FieldValues>({
   /* ================= 5. findai：纯白极简居中 ================= */
   if (variant === "minimal") {
     const softInput =
-      "w-full rounded-2xl border border-transparent bg-neutral-100 px-5 py-4 text-base text-foreground placeholder:text-neutral-400 focus:border-violet-300 focus:bg-white focus:outline-none focus:ring-4 focus:ring-violet-500/10 transition rounded-2xl";
+      "auth-input w-full rounded-2xl border border-transparent bg-muted px-5 py-4 text-base text-foreground placeholder:text-muted-foreground focus:border-primary/40 focus:outline-none focus:ring-4 focus:ring-primary/10 transition";
     return (
       <Form {...form}>
-        <div className="flex min-h-screen w-full flex-col items-center justify-center bg-white px-4 py-12">
-          <span className="flex h-12 w-12 items-center justify-center rounded-2xl bg-violet-600 text-xl font-bold text-white">
+        <div className="flex min-h-screen w-full flex-col items-center justify-center bg-background px-4 py-12">
+          <span className="flex h-12 w-12 items-center justify-center rounded-2xl bg-primary text-xl font-bold text-primary-foreground">
             {initial}
           </span>
           <h1 className="mt-6 text-3xl font-bold tracking-tight text-foreground">{brand}</h1>
-          <p className="mt-2 text-sm text-neutral-400">{tagline}</p>
+          <p className="mt-2 text-sm text-muted-foreground">{tagline}</p>
           <div className="mt-10 w-full max-w-sm">
             <form onSubmit={form.handleSubmit(onSubmit)} className="space-y-4">
               {socialSlot}
               {children}
               {errorBox}
-              {submitBtn("w-full rounded-2xl bg-violet-600 py-4 text-base font-semibold text-white transition hover:bg-violet-700 disabled:opacity-60")}
+              {submitBtn("w-full rounded-2xl bg-primary py-4 text-base font-semibold text-primary-foreground transition hover:opacity-90 disabled:opacity-60")}
             </form>
             {footerNode}
           </div>
-          <p className="mt-16 text-xs text-neutral-300">{brand} — search, ranked by people</p>
+          <p className="mt-16 text-xs text-muted-foreground/60">{brand} — search, ranked by people</p>
         </div>
       </Form>
     );
diff --git a/packages/core/src/kit/chrome.tsx b/packages/core/src/kit/chrome.tsx
index c8aa8c5..eaae517 100644
--- a/packages/core/src/kit/chrome.tsx
+++ b/packages/core/src/kit/chrome.tsx
@@ -48,11 +48,7 @@ export async function SiteChrome({
   const footerGroups = footerGroupsRaw ?? config.footerGroups;
 
   return (
-    <div
-      data-theme={config.id}
-      className={config.themeClass}
-      style={config.cssVars as React.CSSProperties}
-    >
+    <div className={config.themeClass} style={config.cssVars as React.CSSProperties}>
       <ThemeHeader
         brand={brand}
         navItems={navItems}
diff --git a/packages/core/src/kit/types.ts b/packages/core/src/kit/types.ts
index 770545f..0e9fd09 100644
--- a/packages/core/src/kit/types.ts
+++ b/packages/core/src/kit/types.ts
@@ -36,6 +36,10 @@ export interface SiteConfig {
   themeClass?: string;
   /** 登录页布局变体：五站五种形态 */
   authVariant?: "glass" | "gradient" | "editorial" | "terminal" | "minimal" | "split";
+  /** 站点主题标识（<html data-theme>，与 globals.css 的 token 组对应） */
+  themeId?: string;
+  /** 默认深浅主题（light | dark，用户可通过模式切换按钮更改） */
+  defaultTheme?: "light" | "dark";
   /** 中文品牌文案（导航/页脚/hero/搜索占位） */
   brandZh?: {
     name?: string;
diff --git a/packages/core/src/layouts/auth-layout.tsx b/packages/core/src/layouts/auth-layout.tsx
index 3921dac..9f2611b 100644
--- a/packages/core/src/layouts/auth-layout.tsx
+++ b/packages/core/src/layouts/auth-layout.tsx
@@ -3,26 +3,9 @@
 /**
  * # 组件 AuthLayout
  * 说明：认证页容器。布局职责在 FormShell（六种布局变体）；
- *      这里注入 data-theme（由 NEXT_PUBLIC_AUTH_VARIANT 映射），
- *      使输入框/标签/按钮的站点主题化样式（globals.css）在 auth 路由组生效。
+ *      data-theme 由 <html>（locale layout）统一注入，此处不再重复挂载，
+ *      避免子树覆盖 html 的深浅 token 组合。
  */
-const VARIANT_THEME: Record<string, string> = {
-  glass: "ai-stack",
-  gradient: "launchai",
-  editorial: "the-ai-ledger",
-  terminal: "devai-tools",
-  minimal: "findai",
-  split: "ai-stack",
-};
-
 export function AuthLayout({ children }: { children: React.ReactNode }) {
-  const variant = process.env.NEXT_PUBLIC_AUTH_VARIANT || "glass";
-  return (
-    <div
-      data-theme={VARIANT_THEME[variant] ?? "ai-stack"}
-      className="min-h-screen w-full"
-    >
-      {children}
-    </div>
-  );
+  return <div className="min-h-screen w-full">{children}</div>;
 }
diff --git a/packages/core/src/pages/[locale]/layout.tsx b/packages/core/src/pages/[locale]/layout.tsx
index fd9de6d..7785890 100644
--- a/packages/core/src/pages/[locale]/layout.tsx
+++ b/packages/core/src/pages/[locale]/layout.tsx
@@ -32,7 +32,11 @@ export default async function LocaleLayout({
 
   return (
     <ViewTransitions>
-      <html lang={locale} suppressHydrationWarning>
+      <html
+        lang={locale}
+        suppressHydrationWarning
+        data-theme={process.env.NEXT_PUBLIC_THEME_ID || "ai-stack"}
+      >
         <body
           className={cn(
             GeistSans.className,
@@ -46,7 +50,7 @@ export default async function LocaleLayout({
             attribute="class"
             enableSystem
             disableTransitionOnChange
-            defaultTheme="light"
+            defaultTheme={process.env.NEXT_PUBLIC_DEFAULT_THEME || "light"}
           >
             <NextIntlClientProvider locale={locale} messages={messages}>
               {children}
diff --git a/packages/core/src/styles/globals.css b/packages/core/src/styles/globals.css
index b38e58d..305d25d 100644
--- a/packages/core/src/styles/globals.css
+++ b/packages/core/src/styles/globals.css
@@ -121,52 +121,112 @@ html {
 }
 
 /* ============================================================
-   五站视觉签名（Site Identity Layers）
-   每个网站一套独立设计语言：字体 / 底色 / 圆角 / 边框 / 按钮形态
-   由 SiteChrome 的 data-theme 驱动，仅作用于主题表现层
+   五站设计系统 —— 双模式（浅色 / 深色）完整色彩 token + 形态层
+   data-theme 由站点环境变量注入 <html>；.dark 由 next-themes 切换
    ============================================================ */
 
-/* ---------- 1. AI Stack（classic）：深蓝专业 SaaS ----------
-   密度较高、细边框、轻阴影、蓝色主色 */
+/* ---------- 1. AI Stack：深蓝专业（浅：白底蓝主色 / 深：海军蓝） ---------- */
 [data-theme="ai-stack"] {
   --primary: 224 64% 33%;
   --primary-foreground: 0 0% 100%;
   --ring: 224 64% 33%;
+  --radius: 0.625rem;
 }
-[data-theme="ai-stack"] .rounded-xl,
-[data-theme="ai-stack"] .rounded-2xl {
-  border-radius: 0.625rem;
+[data-theme="ai-stack"].dark {
+  --background: 224 45% 10%;
+  --foreground: 210 30% 94%;
+  --card: 224 40% 13%;
+  --secondary: 223 35% 17%;
+  --muted: 223 35% 16%;
+  --muted-foreground: 215 20% 68%;
+  --border: 222 28% 22%;
+  --input: 222 28% 22%;
+  --primary: 224 70% 62%;
+  --primary-foreground: 224 50% 10%;
+  --ring: 224 70% 62%;
 }
-[data-theme="ai-stack"] .group.relative.rounded-xl {
-  box-shadow: 0 1px 2px rgba(15, 23, 42, 0.04);
+[data-theme="ai-stack"] .rounded-xl { border-radius: 0.625rem; }
+[data-theme="ai-stack"] .hero-dark {
+  background: linear-gradient(180deg, hsl(224 55% 12%) 0%, hsl(224 50% 20%) 75%, hsl(var(--background)) 100%);
+}
+[data-theme="ai-stack"] .hero-dark h1 { color: white; }
+[data-theme="ai-stack"] .hero-dark p,
+[data-theme="ai-stack"] .hero-dark span { color: rgba(255, 255, 255, 0.7); }
+[data-theme="ai-stack"] .hero-dark input {
+  background: white;
+  border-color: transparent;
+  color: hsl(224 40% 15%);
+}
+[data-theme="ai-stack"] .hero-dark input::placeholder { color: hsl(220 15% 55%); }
+[data-theme="ai-stack"] .hero-dark .bg-secondary {
+  background-color: rgba(255, 255, 255, 0.12);
+  color: rgba(255, 255, 255, 0.85);
+}
+[data-theme="ai-stack"] .group.relative {
+  border-left: 3px solid transparent;
+  transition: border-color 0.15s ease, box-shadow 0.15s ease;
+}
+[data-theme="ai-stack"] .group.relative:hover {
+  border-left-color: hsl(var(--primary));
+  box-shadow: 0 4px 14px rgba(15, 23, 42, 0.08);
 }
 
-/* ---------- 2. LaunchAI（product）：暖橙活力社区 ----------
-   暖白底、胶囊按钮、大圆角卡片、橙色主色 */
+/* ---------- 2. LaunchAI：暖橙社区（浅：暖白橙 / 深：深棕橙） ---------- */
 [data-theme="launchai"] {
-  --primary: 16 85% 53%;
+  --primary: 16 85% 50%;
   --primary-foreground: 0 0% 100%;
   --background: 30 55% 97%;
   --secondary: 28 50% 92%;
-  --ring: 16 85% 53%;
+  --ring: 16 85% 50%;
+  --radius: 1.1rem;
 }
-[data-theme="launchai"] .bg-background {
-  background-color: hsl(var(--background));
+[data-theme="launchai"].dark {
+  --background: 20 30% 8%;
+  --foreground: 30 40% 92%;
+  --card: 20 25% 11%;
+  --secondary: 20 22% 15%;
+  --muted: 20 22% 14%;
+  --muted-foreground: 28 15% 66%;
+  --border: 22 20% 20%;
+  --input: 22 20% 20%;
+  --primary: 20 90% 56%;
+  --ring: 20 90% 56%;
 }
-[data-theme="launchai"] .rounded-xl { border-radius: 1.1rem; }
-[data-theme="launchai"] .rounded-2xl { border-radius: 1.4rem; }
-[data-theme="launchai"] h1, [data-theme="launchai"] h2 {
-  letter-spacing: -0.02em;
+[data-theme="launchai"] h1, [data-theme="launchai"] h2 { letter-spacing: -0.02em; }
+[data-theme="launchai"] .hero-launch {
+  background: linear-gradient(135deg, hsl(16 90% 48%) 0%, hsl(26 90% 52%) 100%);
+}
+[data-theme="launchai"].dark .hero-launch {
+  background: linear-gradient(135deg, hsl(16 80% 38%) 0%, hsl(26 80% 42%) 100%);
+}
+[data-theme="launchai"] .hero-launch h1,
+[data-theme="launchai"] .hero-launch p { color: white; }
+[data-theme="launchai"] .hero-launch .text-muted-foreground { color: rgba(255, 255, 255, 0.85); }
+[data-theme="launchai"] .hero-launch a.bg-primary,
+[data-theme="launchai"] .hero-launch button.bg-primary {
+  background: white;
+  color: hsl(16 90% 46%);
 }
 
-/* ---------- 3. The AI Ledger（editorial）：报纸编辑风 ----------
-   纸白底、衬线字体、直角、黑主色、无阴影、粗黑分隔 */
+/* ---------- 3. The AI Ledger：报纸（浅：纸白墨黑 / 深：炭黑米白） ---------- */
 [data-theme="the-ai-ledger"] {
   --primary: 24 10% 12%;
   --primary-foreground: 40 40% 98%;
   --background: 42 45% 97%;
-  --border: 30 10% 82%;
-  --radius: 0px;
+  --foreground: 24 10% 12%;
+  --border: 30 10% 80%;
+  --radius: 1px;
+}
+[data-theme="the-ai-ledger"].dark {
+  --background: 30 8% 9%;
+  --foreground: 40 30% 92%;
+  --card: 30 8% 12%;
+  --secondary: 30 6% 15%;
+  --muted: 30 6% 14%;
+  --muted-foreground: 40 15% 65%;
+  --border: 35 10% 26%;
+  --primary: 40 30% 92%;
+  --primary-foreground: 30 10% 10%;
 }
 [data-theme="the-ai-ledger"] {
   font-family: Georgia, "Times New Roman", "Noto Serif SC", serif;
@@ -175,45 +235,47 @@ html {
 [data-theme="the-ai-ledger"] h2,
 [data-theme="the-ai-ledger"] h3 {
   font-family: Georgia, "Times New Roman", "Noto Serif SC", serif;
-  letter-spacing: -0.005em;
 }
 [data-theme="the-ai-ledger"] .rounded-full,
 [data-theme="the-ai-ledger"] .rounded-xl,
 [data-theme="the-ai-ledger"] .rounded-2xl,
-[data-theme="the-ai-ledger"] .rounded-lg {
-  border-radius: 1px;
-}
+[data-theme="the-ai-ledger"] .rounded-lg { border-radius: 1px; }
 [data-theme="the-ai-ledger"] .shadow,
 [data-theme="the-ai-ledger"] .shadow-sm,
-[data-theme="the-ai-ledger"] .shadow-lg {
-  box-shadow: none;
-}
-[data-theme="the-ai-ledger"] .bg-primary,
-[data-theme="the-ai-ledger"] .hover\:bg-primary {
-  background-color: hsl(24 10% 12%);
-}
-[data-theme="the-ai-ledger"] header .rounded-lg {
-  border-radius: 1px;
+[data-theme="the-ai-ledger"] .shadow-lg { box-shadow: none; }
+[data-theme="the-ai-ledger"] header { border-bottom: 3px double hsl(var(--border)); }
+[data-theme="the-ai-ledger"] .hero-mast p:first-of-type {
+  text-transform: uppercase;
+  letter-spacing: 0.35em;
+  font-size: 11px;
 }
+[data-theme="the-ai-ledger"] .group.relative:hover h3 { text-decoration: underline; text-underline-offset: 3px; }
 
-/* ---------- 4. DevAI.tools（niche）：深色终端 ----------
-   深色底、等宽字体、绿色主色、代码面板感 */
+/* ---------- 4. DevAI.tools：终端（深：默认深色 / 浅：日间终端） ---------- */
 [data-theme="devai-tools"] {
+  --primary: 150 60% 38%;
+  --primary-foreground: 0 0% 100%;
+  --background: 150 20% 97%;
+  --foreground: 200 25% 15%;
+  --card: 0 0% 100%;
+  --secondary: 150 15% 92%;
+  --muted: 150 15% 92%;
+  --muted-foreground: 200 15% 40%;
+  --border: 150 15% 82%;
+  --ring: 150 60% 38%;
+}
+[data-theme="devai-tools"].dark {
   --background: 220 25% 7%;
   --foreground: 210 20% 92%;
-  --primary: 150 60% 45%;
-  --primary-foreground: 220 25% 7%;
+  --card: 220 25% 9%;
   --secondary: 220 20% 13%;
   --muted: 220 20% 13%;
   --muted-foreground: 215 15% 62%;
   --border: 218 18% 17%;
+  --input: 218 18% 17%;
+  --primary: 150 60% 45%;
+  --primary-foreground: 220 25% 7%;
   --ring: 150 60% 45%;
-  --card: 220 25% 9%;
-  --popover: 220 25% 9%;
-  --accent: 220 20% 15%;
-}
-[data-theme="devai-tools"] {
-  font-family: ui-sans-serif, system-ui, sans-serif;
 }
 [data-theme="devai-tools"] h1,
 [data-theme="devai-tools"] h2,
@@ -222,166 +284,50 @@ html {
   font-family: ui-monospace, "SF Mono", Menlo, monospace;
   letter-spacing: -0.01em;
 }
-[data-theme="devai-tools"] .bg-background,
+[data-theme="devai-tools"].dark {
+  background-image: repeating-linear-gradient(
+    0deg,
+    hsl(150 60% 45% / 0.015) 0px,
+    hsl(150 60% 45% / 0.015) 1px,
+    transparent 1px,
+    transparent 3px
+  );
+}
 [data-theme="devai-tools"] .group.relative {
-  background-color: hsl(220 25% 9%);
+  border: 1px solid hsl(var(--border));
+  transition: border-color 0.15s ease, box-shadow 0.15s ease;
+}
+[data-theme="devai-tools"].dark .group.relative:hover {
+  border-color: hsl(150 60% 45% / 0.5);
+  box-shadow: 0 0 24px hsl(150 60% 45% / 0.06);
 }
-[data-theme="devai-tools"] .rounded-xl { border-radius: 0.5rem; }
-[data-theme="devai-tools"] .text-primary { color: hsl(150 60% 45%); }
 
-/* ---------- 5. findai（minimal）：极简紫 ----------
-   纯白、无边框卡片、细分隔、紫罗兰、大留白 */
+/* ---------- 5. findai：极简（浅：纯白紫 / 深：深紫黑） ---------- */
 [data-theme="findai"] {
   --primary: 262 65% 52%;
   --primary-foreground: 0 0% 100%;
   --ring: 262 65% 52%;
 }
+[data-theme="findai"].dark {
+  --background: 262 30% 7%;
+  --foreground: 260 30% 92%;
+  --card: 262 25% 10%;
+  --secondary: 262 20% 14%;
+  --muted: 262 20% 13%;
+  --muted-foreground: 260 15% 66%;
+  --border: 262 18% 20%;
+  --ring: 262 65% 60%;
+  --primary: 262 80% 64%;
+}
 [data-theme="findai"] .group.relative {
   border-color: transparent;
   box-shadow: none;
   transition: background-color 0.15s ease;
 }
-[data-theme="findai"] .group.relative:hover {
-  background-color: hsl(262 40% 97%);
-}
-[data-theme="findai"] .shadow-lg {
-  box-shadow: 0 1px 0 rgba(0, 0, 0, 0.04);
-}
-[data-theme="findai"] .rounded-full { border-radius: 999px; }
-
-/* ============================================================
-   深度设计层 v2 —— 每站完整的视觉语言（不只是换色）
-   ============================================================ */
-
-/* ---------- 1. AI Stack：深蓝渐变 Hero + 统计条（专业 SaaS） ---------- */
-[data-theme="ai-stack"] .hero-dark {
-  background: linear-gradient(180deg, hsl(224 60% 14%) 0%, hsl(224 55% 22%) 75%, hsl(var(--background)) 100%);
-}
-[data-theme="ai-stack"] .hero-dark h1 {
-  color: white;
-}
-[data-theme="ai-stack"] .hero-dark p,
-[data-theme="ai-stack"] .hero-dark span {
-  color: rgba(255, 255, 255, 0.65);
-}
-[data-theme="ai-stack"] .hero-dark input {
-  background: white;
-  border-color: transparent;
-}
-[data-theme="ai-stack"] .hero-dark .bg-secondary {
-  background-color: rgba(255, 255, 255, 0.12);
-  color: rgba(255, 255, 255, 0.85);
-}
-[data-theme="ai-stack"] .hero-dark .bg-secondary:hover {
-  background-color: rgba(255, 255, 255, 0.2);
-}
-[data-theme="ai-stack"] .group.relative {
-  border-left: 3px solid transparent;
-  transition: border-color 0.15s ease, box-shadow 0.15s ease, transform 0.15s ease;
-}
-[data-theme="ai-stack"] .group.relative:hover {
-  border-left-color: hsl(224 64% 40%);
-  box-shadow: 0 4px 14px rgba(15, 23, 42, 0.08);
-}
-
-/* ---------- 2. LaunchAI：橙色渐变 Banner + 活力大字 ---------- */
-[data-theme="launchai"] .hero-launch {
-  background: linear-gradient(135deg, hsl(16 90% 50%) 0%, hsl(24 90% 55%) 100%);
-}
-[data-theme="launchai"] .hero-launch h1,
-[data-theme="launchai"] .hero-launch p {
-  color: white;
-}
-[data-theme="launchai"] .hero-launch .text-muted-foreground {
-  color: rgba(255, 255, 255, 0.85);
-}
-[data-theme="launchai"] .hero-launch a.bg-primary,
-[data-theme="launchai"] .hero-launch button.bg-primary {
-  background: white;
-  color: hsl(16 90% 50%);
-}
-[data-theme="launchai"] .border-l-4 { border-left-width: 4px; }
-[data-theme="launchai"] .group.relative:hover {
-  transform: translateY(-1px);
-}
-
-/* ---------- 3. The AI Ledger：黑色报头 + 报纸排版 ---------- */
-[data-theme="the-ai-ledger"] header {
-  border-bottom: 3px double hsl(24 10% 12%);
-}
-[data-theme="the-ai-ledger"] section:first-of-type {
-  border-bottom: 1px solid hsl(24 10% 12%);
-  background: transparent;
-}
-[data-theme="the-ai-ledger"] section:first-of-type h1 {
-  font-size: clamp(2rem, 5vw, 3.5rem);
-  font-weight: 900;
-}
-[data-theme="the-ai-ledger"] .hero-mast p:first-of-type {
-  text-transform: uppercase;
-  letter-spacing: 0.35em;
-  font-size: 11px;
-}
-[data-theme="the-ai-ledger"] .group.relative:hover h3 {
-  text-decoration: underline;
-  text-underline-offset: 3px;
-}
-[data-theme="the-ai-ledger"] .rounded-full.bg-primary,
-[data-theme="the-ai-ledger"] a.bg-primary {
-  border-radius: 1px;
-}
-/* 首页大标题区域居中双细线（报纸报头风格） */
-[data-theme="the-ai-ledger"] .border-b.border-border {
-  border-bottom-style: double;
-  border-bottom-width: 3px;
-}
-
-/* ---------- 4. DevAI.tools：扫描线 + 终端霓虹 ---------- */
-[data-theme="devai-tools"] {
-  background-image: repeating-linear-gradient(
-    0deg,
-    rgba(150, 60% 45% / 0.015) 0px,
-    rgba(150, 60% 45% / 0.015) 1px,
-    transparent 1px,
-    transparent 3px
-  );
-}
-[data-theme="devai-tools"] .group.relative {
-  border: 1px solid hsl(218 18% 17%);
-  transition: border-color 0.15s ease, box-shadow 0.15s ease;
-}
-[data-theme="devai-tools"] .group.relative:hover {
-  border-color: hsl(150 60% 45% / 0.5);
-  box-shadow: 0 0 0 1px hsl(150 60% 45% / 0.15), 0 0 24px hsl(150 60% 45% / 0.06);
-}
-[data-theme="devai-tools"] .rounded-xl.bg-primary {
-  background-color: hsl(150 60% 45%);
-  color: hsl(220 25% 7%);
-}
-[data-theme="devai-tools"] header .bg-secondary {
-  background-color: hsl(220 20% 13%);
-}
-
-/* ---------- 5. findai：聚焦光圈 + 无界卡片 ---------- */
+[data-theme="findai"] .group.relative:hover { background-color: hsl(var(--muted)); }
 [data-theme="findai"] input:focus {
-  box-shadow: 0 0 0 6px hsl(262 65% 52% / 0.08), 0 8px 30px hsl(262 65% 52% / 0.1);
-  border-color: hsl(262 65% 52% / 0.4);
-}
-[data-theme="findai"] .group.relative:hover h3 {
-  color: hsl(262 65% 52%);
-}
-[data-theme="findai"] .rounded-full.border {
-  border-color: hsl(0 0% 90%);
-}
-
-/* LaunchAI hero 斜切签名条 */
-[data-theme="launchai"] section:first-of-type::after {
-  content: "";
-  display: block;
-  height: 18px;
-  margin-top: -18px;
-  background: hsl(var(--background));
-  clip-path: polygon(0 100%, 100% 0, 100% 100%, 0 100%);
+  box-shadow: 0 0 0 6px hsl(var(--primary) / 0.08), 0 8px 30px hsl(var(--primary) / 0.1);
+  border-color: hsl(var(--primary) / 0.4);
 }
 
 /* ============================================================
@@ -392,7 +338,7 @@ html {
 [data-theme="the-ai-ledger"] .auth-input {
   border-radius: 0;
   border: 0;
-  border-bottom: 2px solid hsl(24 10% 70%);
+  border-bottom: 2px solid hsl(var(--border));
   background: transparent;
   font-family: Georgia, "Times New Roman", serif;
   font-size: 1.05rem;
@@ -400,56 +346,43 @@ html {
   padding-right: 0;
 }
 [data-theme="the-ai-ledger"] .auth-input:focus {
-  border-bottom-color: hsl(24 10% 12%);
+  border-bottom-color: hsl(var(--foreground));
   box-shadow: none;
 }
 [data-theme="the-ai-ledger"] form button[type="submit"],
-[data-theme="the-ai-ledger"] form .rounded-lg {
-  border-radius: 1px;
-}
-[data-theme="the-ai-ledger"] form label {
-  font-family: Georgia, serif;
-  letter-spacing: 0.02em;
-}
+[data-theme="the-ai-ledger"] form .rounded-lg { border-radius: 1px; }
 
 /* DevAI.tools：终端等宽输入 */
 [data-theme="devai-tools"] .auth-input {
   border-radius: 0.375rem;
-  border: 1px solid hsl(150 60% 45% / 0.3);
-  background: rgba(0, 0, 0, 0.45);
+  border: 1px solid hsl(var(--border));
+  background: hsl(var(--card));
   font-family: ui-monospace, "SF Mono", Menlo, monospace;
+}
+[data-theme="devai-tools"].dark .auth-input {
   color: hsl(150 40% 88%);
+  border-color: hsl(150 60% 45% / 0.3);
+  background: rgba(0, 0, 0, 0.45);
 }
-[data-theme="devai-tools"] .auth-input::placeholder {
-  color: hsl(150 30% 50% / 0.4);
-}
-[data-theme="devai-tools"] .auth-input:focus {
+[data-theme="devai-tools"].dark .auth-input::placeholder { color: hsl(150 30% 50% / 0.4); }
+[data-theme="devai-tools"].dark .auth-input:focus {
   border-color: hsl(150 60% 45% / 0.7);
   box-shadow: 0 0 0 3px hsl(150 60% 45% / 0.1);
 }
-[data-theme="devai-tools"] form label {
+[data-theme="devai-tools"] form label { font-size: 0.8rem; }
+[data-theme="devai-tools"].dark form label {
   font-family: ui-monospace, Menlo, monospace;
   font-size: 0.75rem;
   color: hsl(150 40% 60% / 0.85);
 }
-[data-theme="devai-tools"] form .rounded-lg {
-  border-radius: 0.375rem;
-  border-color: hsl(150 60% 45% / 0.25);
-  background: rgba(0, 0, 0, 0.3);
-}
 
-/* findai：大圆角浅灰底输入 */
+/* findai：大圆角浅灰输入 */
 [data-theme="findai"] .auth-input {
   border-radius: 1rem;
   background: hsl(0 0% 96%);
 }
-[data-theme="findai"] .auth-input:focus {
-  background: white;
-  box-shadow: 0 0 0 4px hsl(262 65% 52% / 0.1);
-}
-[data-theme="findai"] form .rounded-lg {
-  border-radius: 1rem;
-}
+[data-theme="findai"].dark .auth-input { background: hsl(var(--card)); }
+[data-theme="findai"] .auth-input:focus { background: hsl(var(--background)); }
 
 /* LaunchAI：大圆角输入 */
 [data-theme="launchai"] .auth-input {
@@ -457,6 +390,3 @@ html {
   padding-top: 0.75rem;
   padding-bottom: 0.75rem;
 }
-[data-theme="launchai"] form .rounded-lg {
-  border-radius: 0.875rem;
-}
diff --git a/sites/ai-stack/.env.example b/sites/ai-stack/.env.example
index 564d0a5..e194fba 100644
--- a/sites/ai-stack/.env.example
+++ b/sites/ai-stack/.env.example
@@ -15,6 +15,9 @@ NEXT_PUBLIC_APP_NAME="AI Stack"
 # 登录页品牌模板（分栏侧栏颜色与标语）
 NEXT_PUBLIC_AUTH_ACCENT="222 47% 11%"
 NEXT_PUBLIC_AUTH_VARIANT="glass"
+# 站点主题标识（<html data-theme>）与默认深浅（light | dark，用户可切换）
+NEXT_PUBLIC_THEME_ID="ai-stack"
+NEXT_PUBLIC_DEFAULT_THEME="undefined"
 NEXT_PUBLIC_AUTH_BRAND_TAGLINE="The professional AI tools directory — ranked by the community."
 # 开发阶段免邮箱验证（生产置 false 发送真实验证邮件）
 DEV_SKIP_EMAIL_VERIFY="true"
diff --git a/sites/ai-stack/src/site/brand.tsx b/sites/ai-stack/src/site/brand.tsx
index fa0e048..352a006 100644
--- a/sites/ai-stack/src/site/brand.tsx
+++ b/sites/ai-stack/src/site/brand.tsx
@@ -2,6 +2,7 @@ import type { SiteConfig } from "@/kit/types";
 
 // AI Stack —— 独立站点的全部品牌/导航/页脚配置
 export const siteConfig: SiteConfig = {
+  "themeId": "ai-stack",
   "authVariant": "glass",
   "themeClass": "site-ai-stack",
   "brandZh": {
diff --git a/sites/devai-tools/.env.example b/sites/devai-tools/.env.example
index 47ebe9b..ee6288b 100644
--- a/sites/devai-tools/.env.example
+++ b/sites/devai-tools/.env.example
@@ -15,6 +15,9 @@ NEXT_PUBLIC_APP_NAME="DevAI.tools"
 # 登录页品牌模板（分栏侧栏颜色与标语）
 NEXT_PUBLIC_AUTH_ACCENT="150 60% 30%"
 NEXT_PUBLIC_AUTH_VARIANT="terminal"
+# 站点主题标识（<html data-theme>）与默认深浅（light | dark，用户可切换）
+NEXT_PUBLIC_THEME_ID="devai-tools"
+NEXT_PUBLIC_DEFAULT_THEME="undefined"
 NEXT_PUBLIC_AUTH_BRAND_TAGLINE="AI tools for developers — curated, tested, ranked by the community."
 # 开发阶段免邮箱验证（生产置 false 发送真实验证邮件）
 DEV_SKIP_EMAIL_VERIFY="true"
diff --git a/sites/devai-tools/src/site/brand.tsx b/sites/devai-tools/src/site/brand.tsx
index f2cadab..36962a3 100644
--- a/sites/devai-tools/src/site/brand.tsx
+++ b/sites/devai-tools/src/site/brand.tsx
@@ -2,6 +2,7 @@ import type { SiteConfig } from "@/kit/types";
 
 // DevAI.tools —— 独立站点的全部品牌/导航/页脚配置
 export const siteConfig: SiteConfig = {
+  "themeId": "devai-tools",
   "authVariant": "terminal",
   "themeClass": "site-devai-tools",
   "brandZh": {
diff --git a/sites/findai/.env.example b/sites/findai/.env.example
index 06a62b0..914f9be 100644
--- a/sites/findai/.env.example
+++ b/sites/findai/.env.example
@@ -15,6 +15,9 @@ NEXT_PUBLIC_APP_NAME="findai"
 # 登录页品牌模板（分栏侧栏颜色与标语）
 NEXT_PUBLIC_AUTH_ACCENT="260 70% 52%"
 NEXT_PUBLIC_AUTH_VARIANT="minimal"
+# 站点主题标识（<html data-theme>）与默认深浅（light | dark，用户可切换）
+NEXT_PUBLIC_THEME_ID="findai"
+NEXT_PUBLIC_DEFAULT_THEME="undefined"
 NEXT_PUBLIC_AUTH_BRAND_TAGLINE="The minimal AI tool search engine."
 # 开发阶段免邮箱验证（生产置 false 发送真实验证邮件）
 DEV_SKIP_EMAIL_VERIFY="true"
diff --git a/sites/findai/src/site/brand.tsx b/sites/findai/src/site/brand.tsx
index 8393365..38aeb5e 100644
--- a/sites/findai/src/site/brand.tsx
+++ b/sites/findai/src/site/brand.tsx
@@ -2,6 +2,7 @@ import type { SiteConfig } from "@/kit/types";
 
 // findai —— 独立站点的全部品牌/导航/页脚配置
 export const siteConfig: SiteConfig = {
+  "themeId": "findai",
   "authVariant": "minimal",
   "themeClass": "site-findai",
   "brandZh": {
diff --git a/sites/launchai/.env.example b/sites/launchai/.env.example
index 28201ef..e73b56e 100644
--- a/sites/launchai/.env.example
+++ b/sites/launchai/.env.example
@@ -15,6 +15,9 @@ NEXT_PUBLIC_APP_NAME="LaunchAI"
 # 登录页品牌模板（分栏侧栏颜色与标语）
 NEXT_PUBLIC_AUTH_ACCENT="16 85% 55%"
 NEXT_PUBLIC_AUTH_VARIANT="gradient"
+# 站点主题标识（<html data-theme>）与默认深浅（light | dark，用户可切换）
+NEXT_PUBLIC_THEME_ID="launchai"
+NEXT_PUBLIC_DEFAULT_THEME="undefined"
 NEXT_PUBLIC_AUTH_BRAND_TAGLINE="Discover and upvote today's AI products."
 # 开发阶段免邮箱验证（生产置 false 发送真实验证邮件）
 DEV_SKIP_EMAIL_VERIFY="true"
diff --git a/sites/launchai/src/site/brand.tsx b/sites/launchai/src/site/brand.tsx
index a8f914b..9bda339 100644
--- a/sites/launchai/src/site/brand.tsx
+++ b/sites/launchai/src/site/brand.tsx
@@ -2,6 +2,7 @@ import type { SiteConfig } from "@/kit/types";
 
 // LaunchAI —— 独立站点的全部品牌/导航/页脚配置
 export const siteConfig: SiteConfig = {
+  "themeId": "launchai",
   "authVariant": "gradient",
   "themeClass": "site-launchai",
   "brandZh": {
diff --git a/sites/the-ai-ledger/.env.example b/sites/the-ai-ledger/.env.example
index 3a4dc6b..9e8ee56 100644
--- a/sites/the-ai-ledger/.env.example
+++ b/sites/the-ai-ledger/.env.example
@@ -15,6 +15,9 @@ NEXT_PUBLIC_APP_NAME="The AI Ledger"
 # 登录页品牌模板（分栏侧栏颜色与标语）
 NEXT_PUBLIC_AUTH_ACCENT="36 70% 40%"
 NEXT_PUBLIC_AUTH_VARIANT="editorial"
+# 站点主题标识（<html data-theme>）与默认深浅（light | dark，用户可切换）
+NEXT_PUBLIC_THEME_ID="the-ai-ledger"
+NEXT_PUBLIC_DEFAULT_THEME="undefined"
 NEXT_PUBLIC_AUTH_BRAND_TAGLINE="Independent journalism on AI tools, with a community-ranked directory."
 # 开发阶段免邮箱验证（生产置 false 发送真实验证邮件）
 DEV_SKIP_EMAIL_VERIFY="true"
diff --git a/sites/the-ai-ledger/src/site/brand.tsx b/sites/the-ai-ledger/src/site/brand.tsx
index cdf8f39..b658f97 100644
--- a/sites/the-ai-ledger/src/site/brand.tsx
+++ b/sites/the-ai-ledger/src/site/brand.tsx
@@ -2,6 +2,7 @@ import type { SiteConfig } from "@/kit/types";
 
 // The AI Ledger —— 独立站点的全部品牌/导航/页脚配置
 export const siteConfig: SiteConfig = {
+  "themeId": "the-ai-ledger",
   "authVariant": "editorial",
   "themeClass": "site-the-ai-ledger",
   "brandZh": {