diff --git a/src/layouts/LeftLayout.vue b/src/layouts/LeftLayout.vue
index 2489c54f..6f5f5998 100644
--- a/src/layouts/LeftLayout.vue
+++ b/src/layouts/LeftLayout.vue
@@ -45,6 +45,8 @@ const appStore = useAppStore();
 </script>
 
 <style lang="scss" scoped>
+@use "@/styles/base/mixins" as *;
+
 .layout {
   &__sidebar {
     position: fixed;
@@ -69,7 +71,7 @@ const appStore = useAppStore();
 
       &.has-logo {
         .el-scrollbar {
-          height: calc(100vh - $navbar-height);
+          @include sidebar-scroll-height-with-logo;
         }
       }
 
@@ -131,7 +133,7 @@ const appStore = useAppStore();
 
 .hasTagsView {
   :deep(.app-main) {
-    height: calc(100vh - $navbar-height - $tags-view-height) !important;
+    @include app-main-height-with-tags;
   }
 }
 </style>
diff --git a/src/layouts/MixLayout.vue b/src/layouts/MixLayout.vue
index e73c7dec..581d3313 100644
--- a/src/layouts/MixLayout.vue
+++ b/src/layouts/MixLayout.vue
@@ -229,6 +229,8 @@ watch(
 </script>
 
 <style lang="scss" scoped>
+@use "@/styles/base/mixins" as *;
+
 .layout {
   &__header {
     position: sticky;
@@ -297,8 +299,8 @@ watch(
   }
 
   &__container {
+    @include app-main-height;
     display: flex;
-    height: calc(100vh - $navbar-height);
     padding-top: 0;
 
     .layout__sidebar--left {
@@ -314,7 +316,7 @@ watch(
       }
 
       :deep(.el-scrollbar) {
-        height: calc(100vh - $navbar-height - 50px);
+        @include sidebar-scroll-height-with-toggle;
       }
 
       :deep(.el-menu) {
@@ -329,8 +331,8 @@ watch(
         align-items: center;
         justify-content: center;
         width: 100%;
-        height: 50px;
-        line-height: 50px;
+        height: $sidebar-toggle-height;
+        line-height: $sidebar-toggle-height;
         background-color: var(--menu-background);
         box-shadow: 0 0 6px -2px var(--el-color-primary);
       }
@@ -368,7 +370,7 @@ watch(
 
 :deep(.hasTagsView) {
   .app-main {
-    height: calc(100vh - $navbar-height - $tags-view-height) !important;
+    @include app-main-height-with-tags;
   }
 }
 </style>
diff --git a/src/layouts/TopLayout.vue b/src/layouts/TopLayout.vue
index a07e425f..71cf79fc 100644
--- a/src/layouts/TopLayout.vue
+++ b/src/layouts/TopLayout.vue
@@ -49,6 +49,8 @@ const isLogoCollapsed = computed(() => width.value < 768);
 </script>
 
 <style lang="scss" scoped>
+@use "@/styles/base/mixins" as *;
+
 .layout {
   &__header {
     position: sticky;
@@ -143,14 +145,14 @@ const isLogoCollapsed = computed(() => width.value < 768);
   }
 
   &__main {
-    height: calc(100vh - $navbar-height);
+    @include app-main-height;
     overflow-y: auto;
   }
 }
 
 .hasTagsView {
   :deep(.app-main) {
-    height: calc(100vh - $navbar-height - $tags-view-height) !important;
+    @include app-main-height-with-tags;
   }
 }
 </style>
diff --git a/src/styles/base/_mixins.scss b/src/styles/base/_mixins.scss
new file mode 100644
index 00000000..652c9f6d
--- /dev/null
+++ b/src/styles/base/_mixins.scss
@@ -0,0 +1,68 @@
+/**
+ * 布局 Mixins
+ *
+ * 所有布局组件共享的样式抽象，确保单一来源。
+ *
+ * ═══════════════════════════════════════════════════════════
+ *  主题变量契约（添加新主题时必须定义以下 CSS 变量）
+ * ═══════════════════════════════════════════════════════════
+ *
+ *  --menu-background       菜单背景色
+ *  --menu-text             菜单文字色
+ *  --menu-active-text      菜单激活文字色（通常复用 --el-menu-active-color）
+ *  --menu-hover            菜单悬浮背景色【自动派生——见 _theme.scss 颜色令牌】
+ *  --sidebar-logo-background  Logo 区域背景色
+ *  --sidebar-logo-text-color  Logo 区域文字色
+ *
+ *  自动派生规则：--menu-hover 通过 color-mix() 从 --menu-background 派生，
+ *  因此新主题只需定义 --menu-background，hover 颜色自动生成。
+ *  如需覆盖自动派生值，显式设置 --menu-hover 即可。
+ */
+
+@use "variables" as *;
+
+// ============================================
+// 布局计算 Mixins
+// ============================================
+
+/**
+ * 计算主内容区高度（考虑 TagsView 是否存在）
+ *
+ * 使用场景：各布局文件中的 .hasTagsView 样式块
+ *
+ * @example
+ *   .hasTagsView {
+ *     :deep(.app-main) {
+ *       @include app-main-height-with-tags;
+ *     }
+ *   }
+ */
+@mixin app-main-height-with-tags {
+  height: calc(100vh - $navbar-height - $tags-view-height) !important;
+}
+
+/**
+ * 主内容区基础高度（无 TagsView）
+ *
+ * @example
+ *   .layout__main {
+ *     @include app-main-height;
+ *   }
+ */
+@mixin app-main-height {
+  height: calc(100vh - $navbar-height);
+}
+
+/**
+ * 侧边栏滚动区高度（带 Logo 时）
+ */
+@mixin sidebar-scroll-height-with-logo {
+  height: calc(100vh - $navbar-height);
+}
+
+/**
+ * 侧边栏滚动区高度（带底部折叠按钮时，如 MixLayout 左侧）
+ */
+@mixin sidebar-scroll-height-with-toggle {
+  height: calc(100vh - $navbar-height - $sidebar-toggle-height);
+}
diff --git a/src/styles/base/_theme.scss b/src/styles/base/_theme.scss
index 74cd2432..3f2738dc 100644
--- a/src/styles/base/_theme.scss
+++ b/src/styles/base/_theme.scss
@@ -1,17 +1,45 @@
 /**
  * 主题变量定义
+ *
+ * ═══════════════════════════════════════════════════════════
+ *  主题变量契约
+ * ═══════════════════════════════════════════════════════════
+ *
+ *  新增主题只需定义以下变量，其余自动派生：
+ *
+ *  必须定义：
+ *    --menu-background        菜单背景色
+ *    --menu-text              菜单文字色
+ *    --menu-active-text       菜单激活文字色
+ *    --sidebar-logo-background  Logo 区域背景色
+ *    --sidebar-logo-text-color  Logo 区域文字色
+ *
+ *  可选覆盖（有自动派生默认值）：
+ *    --menu-hover             菜单悬浮背景色
+ *      → 浅色主题：从 --el-color-primary 与背景混合派生
+ *      → 深色主题：半透明黑色叠加层，自适应动态背景
+ *      → 可显式覆盖以微调
  */
 
+// ============================================
+// SCSS 颜色令牌（构建时源）
+// ============================================
+
+$menu-bg-light: #fff;
+$menu-hover-light: #e6f4ff; // 设计指定色，非纯推导
+
+$menu-bg-classic-blue: #304156;
+
 // ============================================
 // 默认主题（浅色 + 白色侧边栏）
 // ============================================
 
 :root {
   // 菜单
-  --menu-background: #fff;
+  --menu-background: #{$menu-bg-light};
   --menu-text: #606266;
   --menu-active-text: var(--el-menu-active-color);
-  --menu-hover: #e6f4ff;
+  --menu-hover: #{$menu-hover-light};
 
   // 侧边栏 Logo
   --sidebar-logo-background: #fafafa;
@@ -57,10 +85,11 @@
 // ============================================
 
 html.sidebar-color-blue {
-  --menu-background: #304156;
+  --menu-background: #{$menu-bg-classic-blue};
   --menu-text: #bfcbd9;
   --menu-active-text: var(--el-menu-active-color);
-  --menu-hover: #263445;
+  // 自动派生：背景色加深 20% → #263445
+  --menu-hover: color-mix(in srgb, var(--menu-background) 80%, #000 20%);
   --sidebar-logo-background: #2d3748;
   --sidebar-logo-text-color: #fff;
 }
@@ -73,6 +102,7 @@ html.dark {
   --menu-background: var(--el-bg-color-overlay);
   --menu-text: #fff;
   --menu-active-text: var(--el-menu-active-color);
+  // 半透明叠加层：自适应 Element Plus 动态 overlay 背景色
   --menu-hover: rgb(0 0 0 / 20%);
   --sidebar-logo-background: rgb(0 0 0 / 20%);
   --sidebar-logo-text-color: #fff;
diff --git a/src/styles/base/_variables.scss b/src/styles/base/_variables.scss
index 8ec4ccbd..4e565522 100644
--- a/src/styles/base/_variables.scss
+++ b/src/styles/base/_variables.scss
@@ -11,6 +11,7 @@ $sidebar-width: 210px;
 $sidebar-width-collapsed: 54px;
 $navbar-height: 50px;
 $tags-view-height: 40px;
+$sidebar-toggle-height: 50px;
 
 // ============================================
 // CSS 变量映射（供组件和 SCSS 使用）
diff --git a/src/views/demo/api/apifox.vue b/src/views/demo/api/apifox.vue
index ea4593c1..a6eaea04 100644
--- a/src/views/demo/api/apifox.vue
+++ b/src/views/demo/api/apifox.vue
@@ -11,17 +11,15 @@
 </template>
 
 <style lang="scss" scoped>
-/** 关闭tag标签  */
+@use "@/styles/base/variables" as *;
+
 .page-container {
-  /* 50px = navbar = 50px */
-  height: calc(100vh - 50px);
+  height: calc(100vh - $navbar-height);
 }
 
-/** 开启tag标签  */
 .hasTagsView {
   .page-container {
-    /* 84px = navbar + tags-view = 50px + 34px */
-    height: calc(100vh - 84px);
+    height: calc(100vh - $navbar-height - $tags-view-height);
   }
 }
 </style>
diff --git a/src/views/demo/internal-doc.vue b/src/views/demo/internal-doc.vue
index 16ac5824..baa54d7c 100644
--- a/src/views/demo/internal-doc.vue
+++ b/src/views/demo/internal-doc.vue
@@ -4,17 +4,15 @@
   </div>
 </template>
 <style lang="scss" scoped>
-/** 关闭tag标签  */
+@use "@/styles/base/variables" as *;
+
 .page-container {
-  /* 50px = navbar = 50px */
-  height: calc(100vh - 50px);
+  height: calc(100vh - $navbar-height);
 }
 
-/** 开启tag标签  */
 .hasTagsView {
   .page-container {
-    /* 84px = navbar + tags-view = 50px + 34px */
-    height: calc(100vh - 84px);
+    height: calc(100vh - $navbar-height - $tags-view-height);
   }
 }