diff --git a/app/page.tsx b/app/page.tsx
index 0a8196b..72f3dbf 100644
--- a/app/page.tsx
+++ b/app/page.tsx
@@ -2,7 +2,8 @@ import Link from "next/link";
 import PageShell from "@/components/page-shell";
 import { BookOpen, BrainCircuit, Compass, Sparkles } from "lucide-react";
 import { ZenCard } from "@/components/ui/zen-card";
-import { APP_CONTAINER } from "@/lib/layout";
+import { HOME_CONTAINER } from "@/lib/layout";
+import { TaijiIcon } from "@/components/svg/taiji";
 
 const MODULES = [
   {
@@ -37,9 +38,9 @@ const MODULES = [
 
 export default function Home() {
   return (
-    <PageShell className={`${APP_CONTAINER} py-10 sm:py-14`}>
+    <PageShell className={`${HOME_CONTAINER} py-10 sm:py-14`}>
       <div className="mb-10 text-center">
-        <p className="text-4xl opacity-30">☯</p>
+        <TaijiIcon className="mx-auto h-12 w-12 opacity-80" />
         <h1 className="mt-2 text-3xl font-bold tracking-[0.2em]">知命阁</h1>
         <p className="mt-3 text-sm tracking-wide text-muted-foreground">
           融合周易智慧与人工智能
diff --git a/components/layout/mode-workspace.tsx b/components/layout/mode-workspace.tsx
index 8fa84fc..f2de4f4 100644
--- a/components/layout/mode-workspace.tsx
+++ b/components/layout/mode-workspace.tsx
@@ -1,7 +1,7 @@
 "use client";
 
 import { Sparkles } from "lucide-react";
-import { APP_CONTAINER } from "@/lib/layout";
+import { MODE_CONTAINER } from "@/lib/layout";
 
 export function ModeWorkspace({
   children,
@@ -13,7 +13,7 @@ export function ModeWorkspace({
   aiTitle?: string;
 }) {
   return (
-    <div className={`${APP_CONTAINER} py-6 lg:py-8`}>
+    <div className={`${MODE_CONTAINER} py-6 lg:py-8`}>
       <div className="grid gap-6 lg:grid-cols-2 lg:items-stretch lg:gap-8 xl:gap-10">
         <div className="grid h-full min-h-0 auto-rows-fr gap-5 lg:min-h-[calc(100vh-9rem)]">
           {children}
diff --git a/components/layout/taiji-backdrop.tsx b/components/layout/taiji-backdrop.tsx
index 44a07c5..653d15a 100644
--- a/components/layout/taiji-backdrop.tsx
+++ b/components/layout/taiji-backdrop.tsx
@@ -1,15 +1,15 @@
 import { TaijiWatermark } from "@/components/svg/taiji";
 
-/** 全页太极背景水印 */
+/** 全页太极背景水印（居中，不撑满超宽屏） */
 export default function TaijiBackdrop() {
   return (
     <div
       aria-hidden
-      className="pointer-events-none fixed inset-0 -z-10 overflow-hidden bg-background/80"
+      className="pointer-events-none fixed inset-0 -z-10 overflow-hidden"
     >
-      <TaijiWatermark className="absolute left-1/2 top-1/2 h-[min(95vmin,1200px)] w-[min(95vmin,1200px)] -translate-x-1/2 -translate-y-1/2 opacity-90" />
-      <TaijiWatermark className="absolute -right-[8%] top-[6%] h-[min(42vmin,520px)] w-[min(42vmin,520px)] opacity-45" />
-      <TaijiWatermark className="absolute -left-[10%] bottom-[4%] h-[min(38vmin,460px)] w-[min(38vmin,460px)] opacity-40" />
+      <TaijiWatermark className="absolute left-1/2 top-1/2 h-[min(72vmin,720px)] w-[min(72vmin,720px)] -translate-x-1/2 -translate-y-1/2" />
+      <TaijiWatermark className="absolute right-[8%] top-[10%] hidden h-[min(28vmin,320px)] w-[min(28vmin,320px)] opacity-60 lg:block" />
+      <TaijiWatermark className="absolute bottom-[8%] left-[8%] hidden h-[min(24vmin,280px)] w-[min(24vmin,280px)] opacity-50 lg:block" />
     </div>
   );
 }
diff --git a/components/svg/taiji.tsx b/components/svg/taiji.tsx
index 1cc73a7..755f5e0 100644
--- a/components/svg/taiji.tsx
+++ b/components/svg/taiji.tsx
@@ -1,10 +1,7 @@
 import React from "react";
 import { cn } from "@/lib/utils";
 
-const YANG = "fill-stone-100 dark:fill-stone-200";
-const YIN = "fill-stone-800 dark:fill-stone-900";
-
-/** 太极阴阳鱼图标（页眉 Logo） */
+/** 太极阴阳鱼图标（页眉 Logo）— 亮色模式描边保证阴阳分界可见 */
 export const TaijiIcon = React.memo(function TaijiIcon({
   className,
 }: {
@@ -14,16 +11,21 @@ export const TaijiIcon = React.memo(function TaijiIcon({
     <svg
       viewBox="0 0 64 64"
       xmlns="http://www.w3.org/2000/svg"
-      className={cn("h-7 w-7 shrink-0 drop-shadow-sm", className)}
+      className={cn("h-7 w-7 shrink-0", className)}
       aria-hidden
     >
-      <circle cx="32" cy="32" r="30" className={YANG} />
+      <circle
+        cx="32"
+        cy="32"
+        r="30"
+        className="fill-white stroke-stone-600 stroke-[1.5] dark:fill-stone-200 dark:stroke-stone-400"
+      />
       <path
         d="M32 2a30 30 0 0 1 0 60 15 15 0 0 1 0-30 15 15 0 0 0 0-30z"
-        className={YIN}
+        className="fill-stone-800 dark:fill-stone-900"
       />
-      <circle cx="32" cy="17" r="5" className={YANG} />
-      <circle cx="32" cy="47" r="5" className={YIN} />
+      <circle cx="32" cy="17" r="5" className="fill-white dark:fill-stone-200" />
+      <circle cx="32" cy="47" r="5" className="fill-stone-800 dark:fill-stone-900" />
     </svg>
   );
 });
@@ -41,13 +43,24 @@ export function TaijiWatermark({
       className={className}
       aria-hidden
     >
-      <circle cx="100" cy="100" r="98" className={`${YANG} opacity-[0.35]`} />
+      <circle
+        cx="100"
+        cy="100"
+        r="98"
+        className="fill-none stroke-stone-400/30 stroke-[0.75] dark:stroke-stone-500/25"
+      />
+      <circle
+        cx="100"
+        cy="100"
+        r="98"
+        className="fill-white/40 dark:fill-stone-200/10"
+      />
       <path
         d="M100 2a98 98 0 0 1 0 196 49 49 0 0 1 0-98 49 49 0 0 0 0-98z"
-        className={`${YIN} opacity-[0.08] dark:opacity-[0.12]`}
+        className="fill-stone-600/10 dark:fill-stone-300/12"
       />
-      <circle cx="100" cy="51" r="10" className={`${YANG} opacity-50`} />
-      <circle cx="100" cy="149" r="10" className={`${YIN} opacity-20 dark:opacity-30`} />
+      <circle cx="100" cy="51" r="10" className="fill-white/60 dark:fill-stone-200/20" />
+      <circle cx="100" cy="149" r="10" className="fill-stone-600/15 dark:fill-stone-300/20" />
     </svg>
   );
 }
diff --git a/lib/layout.ts b/lib/layout.ts
index 69b4ab9..b3f764f 100644
--- a/lib/layout.ts
+++ b/lib/layout.ts
@@ -1,3 +1,10 @@
-/** 全站内容区宽度：手机满宽，带鱼屏最大约 1920px 并留边距 */
-export const APP_CONTAINER =
-  "mx-auto w-full max-w-[min(100%,1920px)] px-4 sm:px-6 lg:px-8 xl:px-12 2xl:px-16";
+const CENTER = "mx-auto w-full px-4 sm:px-6 lg:px-8";
+
+/** 页眉 / 页脚 / 学习 / 测算页标题 — 居中留白，最大约 1152px */
+export const APP_CONTAINER = `${CENTER} max-w-6xl`;
+
+/** 首页单列 — 更窄一些 */
+export const HOME_CONTAINER = `${CENTER} max-w-4xl`;
+
+/** 双栏测算工作区 — 与全站同宽，避免带鱼屏拉满 */
+export const MODE_CONTAINER = `${CENTER} max-w-6xl xl:px-10`;