refactor: remove exact cross-layer css duplicates

app/config/architecture-inventory.json

@@ -309,13 +309,13 @@
   "code_hotspots": [
     {
       "path": "frontend/styles/styles.css",
-      "bytes": 361776,
-      "lines": 15465
+      "bytes": 361501,
+      "lines": 15450
     },
     {
       "path": "frontend/styles/redesign-v2.css",
-      "bytes": 263539,
-      "lines": 8570
+      "bytes": 263467,
+      "lines": 8569
     },
     {
       "path": "frontend/index.html",
@@ -344,8 +344,8 @@
     },
     {
       "path": "frontend/styles/renovation.css",
-      "bytes": 83949,
-      "lines": 1553
+      "bytes": 83812,
+      "lines": 1550
     },
     {
       "path": "frontend/pages/heaven/page.css",

app/frontend/styles/redesign-v2.css

@@ -4318,7 +4318,6 @@ body.sidebar-collapsed .status-bar { left: 64px; }
 #dragonView .dragon-operation-table .dragon-col-direction { width: 72px; }
 #dragonView .dragon-operation-table .dragon-col-number { width: 82px; }
 #dragonView .dragon-operation-table .dragon-col-seat { width: 190px; }
-#dragonView .dragon-operation-table .dragon-col-reason { width: auto; }
 #dragonView .dragon-operation-table :is(th, td).row-number { padding-inline: 8px; text-align: center; }
 #dragonView .dragon-operation-table td.stock-code { font-variant-numeric: tabular-nums; }
 #dragonView .dragon-operation-table thead th { position: sticky; top: 0; z-index: 2; background: #fafbfc; }

app/frontend/styles/renovation.css

@@ -127,7 +127,6 @@ body.sidebar-collapsed .app-main { margin-left: 0; }
   background: transparent;
 }
 
-.overview-strip .sentiment-block { padding-left: 0; }
 .overview-strip .sentiment-gauge { width: 26px; height: 26px; flex: 0 0 26px; border-width: 2px; font-size: 10px; }
 .overview-strip .sentiment-text { font-size: 12px; white-space: nowrap; }
 .overview-strip .metric-label { color: var(--text-tertiary); font-size: 10.5px; white-space: nowrap; }
@@ -160,8 +159,6 @@ body.sidebar-collapsed .app-main { margin-left: 0; }
 .overview-strip[data-overview-expanded="true"] .metric { min-height: 76px; align-items: flex-start; justify-content: center; flex-direction: column; gap: 4px; }
 .overview-strip[data-overview-expanded="true"] .sentiment-block { flex-direction: row; justify-content: flex-start; align-items: center; }
 .overview-strip[data-overview-expanded="true"] .sentiment-gauge { width: 48px; height: 48px; flex-basis: 48px; font-size: 13px; }
-.overview-strip[data-overview-expanded="true"] .metric-value { font-size: 18px; }
-
 /* Page frame and shared information architecture. */
 .workspace-view,
 body[data-active-view="screenerView"] .workspace-view,

app/frontend/styles/styles.css

@@ -666,10 +666,6 @@ time {
   box-shadow: var(--shadow-soft);
 }
 
-.workspace-view.active-view {
-  display: block;
-}
-
 .workspace-view.active-view.view-entering {
   animation: view-enter var(--motion-medium) var(--ease-out) both;
 }
@@ -4745,10 +4741,6 @@ textarea {
   outline-color: rgba(29, 101, 193, 0.48);
 }
 
-body.sidebar-collapsed {
-  grid-template-columns: 64px minmax(0, 1fr);
-}
-
 body.sidebar-collapsed .module-nav {
   width: 64px;
   padding-right: 7px;
@@ -5369,8 +5361,6 @@ body.sidebar-collapsed .sidebar-collapse-button .lucide {
   border-right: 1px solid var(--border);
   transition: background-color var(--motion-medium) ease, opacity var(--motion-medium) ease;
 }
-.rotation-day:last-child { border-right: 0; }
-
 .rotation-day header { display: grid; gap: 2px; margin-bottom: 8px; }
 .rotation-day header time { font-size: 12px; font-weight: 700; }
 .rotation-day header span { color: var(--text-secondary); font-size: 10px; }
@@ -7130,11 +7120,6 @@ body.sidebar-collapsed .sidebar-collapse-button .lucide {
   box-shadow: 1px 0 0 var(--border);
 }
 
-#screenerView .probability-value strong,
-#screenerView .probability-value small {
-  display: block;
-}
-
 #screenerView .probability-value small {
   margin-top: 3px;
   color: var(--text-secondary);

app/tests/e2e/app-shell.spec.js

@@ -1803,6 +1803,30 @@ test("heart breathing prepares once then contracts on each exhale", async ({ pag
   await expect(page.locator(".heart-breath-ripple span").first()).toHaveCSS("transition-duration", "4s");
 });
 
+test("stylesheet layers do not repeat identical top-level rules", async ({ page }) => {
+  await mockApplication(page, session("admin", true));
+  await page.goto("/index.html");
+
+  const duplicates = await page.evaluate(() => {
+    const occurrences = new Map();
+    for (const sheet of Array.from(document.styleSheets)) {
+      const href = sheet.href ? new URL(sheet.href).pathname : "inline";
+      for (const rule of Array.from(sheet.cssRules || [])) {
+        if (typeof rule.selectorText !== "string" || !rule.style) continue;
+        const key = `${rule.selectorText}\u0000${rule.style.cssText}`;
+        const rows = occurrences.get(key) || [];
+        rows.push(href);
+        occurrences.set(key, rows);
+      }
+    }
+    return Array.from(occurrences.entries())
+      .filter(([, paths]) => new Set(paths).size > 1)
+      .map(([rule, paths]) => ({ rule, paths }));
+  });
+
+  expect(duplicates).toEqual([]);
+});
+
 test("mobile shell stays within the viewport", async ({ page }) => {
   await page.setViewportSize({ width: 375, height: 812 });
   await mockApplication(page, session("user", true));

app/tests/preservation_helpers.py

@@ -29,6 +29,34 @@ RETIRED_FRONTEND_SOURCE_RANGES = (
 )
 AUDITED_FRONTEND_SOURCE_LINE_COUNT = 9283
 
+# CR-12 removes only declarations that are repeated verbatim by a later
+# stylesheet layer under the same top-level cascade context. Keeping the exact
+# source fragments here makes every other byte of the accepted CSS baseline a
+# preservation requirement.
+AUDITED_CSS_RETIREMENTS = {
+    "styles.css": (
+        ".workspace-view.active-view {\n  display: block;\n}\n\n",
+        "body.sidebar-collapsed {\n  grid-template-columns: 64px minmax(0, 1fr);\n}\n\n",
+        ".rotation-day:last-child { border-right: 0; }\n\n",
+        (
+            "#screenerView .probability-value strong,\n"
+            "#screenerView .probability-value small {\n"
+            "  display: block;\n"
+            "}\n\n"
+        ),
+    ),
+    "renovation.css": (
+        ".overview-strip .sentiment-block { padding-left: 0; }\n",
+        (
+            '.overview-strip[data-overview-expanded="true"] .metric-value '
+            "{ font-size: 18px; }\n\n"
+        ),
+    ),
+    "redesign-v2.css": (
+        "#dragonView .dragon-operation-table .dragon-col-reason { width: auto; }\n",
+    ),
+}
+
 
 def sha256(path: Path) -> str:
     return hashlib.sha256(path.read_bytes()).hexdigest()
@@ -123,6 +151,17 @@ def assert_moved_asset_matches(
     frontend_relative: str | None = None,
 ) -> None:
     target_relative = frontend_relative or original_relative
+    if original_relative in AUDITED_CSS_RETIREMENTS:
+        original = (ORIGINAL_STATIC / original_relative).read_text(encoding="utf-8")
+        for retired in AUDITED_CSS_RETIREMENTS[original_relative]:
+            testcase.assertEqual(original.count(retired), 1, retired)
+            original = original.replace(retired, "", 1)
+        testcase.assertEqual(
+            (FRONTEND_ROOT / target_relative).read_text(encoding="utf-8"),
+            original,
+            original_relative,
+        )
+        return
     testcase.assertEqual(
         sha256(FRONTEND_ROOT / target_relative),
         sha256(ORIGINAL_STATIC / original_relative),

app/tests/test_preservation_slice_frontend.py

@@ -44,7 +44,7 @@ class FrontendPreservationSliceTests(unittest.TestCase):
             (ORIGINAL_STATIC / "index.html").read_text(encoding="utf-8"),
         )
 
-    def test_complete_stylesheet_stack_is_byte_identical_after_relocation(self) -> None:
+    def test_stylesheet_stack_matches_baseline_after_audited_retirements(self) -> None:
         for original, migrated in (
             ("shared/tokens.css", "shared/tokens.css"),
             ("styles.css", "styles/styles.css"),

docs/governance/code-reduction.md

@@ -29,6 +29,7 @@
 | CR-09 | 应用服务门面 | 两个仅服务股池iFinD补全的方法仍错位在全局`DashboardService` | 原函数体机械归位到`PoolServiceMixin` | 已完成 |
 | CR-10 | Repository所有权 | 五行行业阶段覆盖的三项持久化方法仍错位在根级数据库门面 | 原函数体机械归位到问天Repository，兼容数据继续保留 | 已完成 |
 | CR-11 | 后台任务生命周期 | 导入应用即启动调度线程，启动早于端口绑定，停止只置位但不等待 | 运行时显式启停，每个Runner只拥有一个可等待的调度线程 | 已完成 |
+| CR-12 | CSS跨层精确重复 | 七层样式保留多次视觉改造形成的重复顶层规则，前层声明被后层逐字覆盖 | 只删除能够由CSSOM证明完全重复的前层规则，并建立浏览器级重复门禁 | 已完成 |
 
 ## CR-01验收口径
 
@@ -294,6 +295,32 @@
 `xiaobai-reduction-11-runtime-connectivity-fix-20260802`；后续解势修正检查点为
 `xiaobai-reduction-11-heaven-interpret-fix-20260802`。
 
+## CR-12验收口径
+
+- 本批只处理不同样式文件中、同为顶层、选择器与完整声明逐字等价的规则；媒体查询、伪状态、
+  动画、问天隔离样式以及仅外形相似的规则不进入删除范围。
+- 删除的必须是较早加载的副本，较晚层继续提供完全相同的最终声明；样式加载顺序、变量、HTML、
+  JavaScript和主题切换逻辑均不改变。
+- 迁移保真测试必须逐段登记允许退休的原始CSS文本，除登记片段外，其余源码继续与原版逐字符相等。
+- 浏览器必须验证跨层顶层精确重复为零，并通过日间、夜间、桌面、390px移动端及全站交互回归。
+
+## CR-12结果
+
+- 通过浏览器CSSOM扫描七层运行样式，共发现57组完整重复规则；本批只批准其中7组跨文件顶层重复，
+  分别涉及工作区显示、折叠侧栏、板块轮动末列、选股概率值、摘要条两项声明及龙虎榜原因列。
+  其余50组位于同文件或嵌套媒体条件等更复杂环境，证据不足，继续保留。
+- 删除7条较早加载的规则，三个生产CSS文件净减少19行、480字节；后层最终规则、选择器优先级与
+  加载顺序均未改变，没有新增兼容覆盖或第二套样式实现。
+- 新增浏览器CSSOM门禁，任何两个样式层再次出现相同顶层选择器与完整声明都会失败；迁移保真门禁
+  只允许已登记的7个精确源码片段退休，其他CSS差异仍会失败。
+- 真实`8797`页面复核情绪周期日间/夜间、龙虎榜和390×844移动端；三个受影响节点的计算样式
+  与删除前一致，移动端无横向溢出。候选330项、CSS/前端契约33项、迁移对照63项及46项
+  Playwright全部通过，24个JavaScript文件、API/架构注册表和SQLite完整性检查通过。
+- 本批不修改页面布局、颜色、字体、间距、响应式规则、主题、动画、业务功能、API、数据库或部署。
+
+本批基线为`xiaobai-reduction-11-heaven-interpret-fix-20260802`；检查点为
+`xiaobai-reduction-12-css-exact-duplicates-20260802`。
+
 ## 人工验收记录
 
 - 2026-08-01：用户检查CR-02与CR-03运行结果，确认未发现明显异常。本记录仅表示本轮可见功能与