diff --git a/src/i18n/easyMode.ts b/src/i18n/easyMode.ts
index b573fc5..a41daf6 100644
--- a/src/i18n/easyMode.ts
+++ b/src/i18n/easyMode.ts
@@ -14,8 +14,8 @@ export const easyModeZhCN = {
   "easyMode.guide.toggleOpen": "点击开启操作指引",
   "easyMode.guide.toggleClose": "点击关闭操作指引",
   "easyMode.guide.close": "关闭指导",
-  "easyMode.theme.light": "明亮主题",
-  "easyMode.theme.dark": "暗色主题",
+  "easyMode.theme.light": "亮色",
+  "easyMode.theme.dark": "暗色",
   "easyMode.language.switch": "切换语言",
   "easyMode.exit": "退出新手模式",
   "easyMode.exitTitle": "返回常规控制台",
@@ -96,8 +96,8 @@ export const easyModeEn: Record<keyof typeof easyModeZhCN, string> = {
   "easyMode.guide.toggleOpen": "Click to open interactive guide",
   "easyMode.guide.toggleClose": "Click to close interactive guide",
   "easyMode.guide.close": "Close guide",
-  "easyMode.theme.light": "Light theme",
-  "easyMode.theme.dark": "Dark theme",
+  "easyMode.theme.light": "Light",
+  "easyMode.theme.dark": "Dark",
   "easyMode.language.switch": "Switch language",
   "easyMode.exit": "Exit Beginner Mode",
   "easyMode.exitTitle": "Return to standard console",
@@ -178,8 +178,8 @@ export const easyModeJa: Record<keyof typeof easyModeZhCN, string> = {
   "easyMode.guide.toggleOpen": "クリックして操作ガイドを開始",
   "easyMode.guide.toggleClose": "クリックして操作ガイドを閉じる",
   "easyMode.guide.close": "ガイドを閉じる",
-  "easyMode.theme.light": "ライトテーマ",
-  "easyMode.theme.dark": "ダークテーマ",
+  "easyMode.theme.light": "ライト",
+  "easyMode.theme.dark": "ダーク",
   "easyMode.language.switch": "言語を切り替え",
   "easyMode.exit": "ビギナーモードを終了",
   "easyMode.exitTitle": "通常コンソールに戻る",
diff --git a/src/i18n/ja.ts b/src/i18n/ja.ts
index 25b5321..3a510f1 100644
--- a/src/i18n/ja.ts
+++ b/src/i18n/ja.ts
@@ -221,10 +221,10 @@ export const jaOverrides = {
   'apiAccess.models.aliasPlaceholder': 'モデル別名（任意）',
   'apiAccess.models.remove': 'モデルを削除',
   'app.language': '言語',
-  'app.theme.light': 'ライトモード',
-  'app.theme.dark': 'ダークモード',
+  'app.theme.light': 'ライト',
+  'app.theme.dark': 'ダーク',
   'app.theme.label': '外観モード',
-  'app.theme.system': 'システムに従う',
+  'app.theme.system': '自動',
   'app.theme.switchToSystem': 'システムの外観に合わせて自動的に切り替え',
   'app.theme.switchToLight': 'ライトモードに切り替え',
   'app.theme.switchToDark': 'ダークモードに切り替え',
diff --git a/src/i18n/locales/en.ts b/src/i18n/locales/en.ts
index 9459c9b..14b89f5 100644
--- a/src/i18n/locales/en.ts
+++ b/src/i18n/locales/en.ts
@@ -170,10 +170,10 @@ export const en: Record<MessageKey, string> = {
   'apiAccess.models.aliasPlaceholder': 'Model alias (optional)',
   'apiAccess.models.remove': 'Remove model',
   'app.language': 'Language',
-  'app.theme.light': 'Light mode',
-  'app.theme.dark': 'Dark mode',
+  'app.theme.light': 'Light',
+  'app.theme.dark': 'Dark',
   'app.theme.label': 'Appearance',
-  'app.theme.system': 'Follow system',
+  'app.theme.system': 'Auto',
   'app.theme.switchToSystem': 'Automatically match the system appearance',
   'app.theme.switchToLight': 'Switch to light mode',
   'app.theme.switchToDark': 'Switch to dark mode',
diff --git a/src/i18n/locales/zh-CN.ts b/src/i18n/locales/zh-CN.ts
index dddda91..3cd84f0 100644
--- a/src/i18n/locales/zh-CN.ts
+++ b/src/i18n/locales/zh-CN.ts
@@ -169,13 +169,13 @@ export const zhCN = {
   'apiAccess.models.aliasPlaceholder': '模型别名（可选）',
   'apiAccess.models.remove': '删除模型',
   'app.language': '语言',
-  'app.theme.light': '日间模式',
-  'app.theme.dark': '夜间模式',
+  'app.theme.light': '亮色',
+  'app.theme.dark': '暗色',
   'app.theme.label': '外观模式',
-  'app.theme.system': '跟随系统',
-  'app.theme.switchToSystem': '随系统自动切换日间和夜间模式',
-  'app.theme.switchToLight': '切换到日间模式',
-  'app.theme.switchToDark': '切换到夜间模式',
+  'app.theme.system': '自动',
+  'app.theme.switchToSystem': '随系统自动切换亮色和暗色',
+  'app.theme.switchToLight': '切换到亮色',
+  'app.theme.switchToDark': '切换到暗色',
   'app.desktopConsole': '桌面控制台',
   'app.navigation': '主导航',
   'app.nav.easy': '新手模式',
diff --git a/src/i18n/traditional.ts b/src/i18n/traditional.ts
index b647e9e..3fce75c 100644
--- a/src/i18n/traditional.ts
+++ b/src/i18n/traditional.ts
@@ -1,5 +1,5 @@
 const phraseReplacements: ReadonlyArray<readonly [string, string]> = [
-  ['随系统自动切换日间和夜间模式', '隨系統自動切換日間和夜間模式'],
+  ['随系统自动切换亮色和暗色', '隨系統自動切換亮色和暗色'],
   ['跟随系统', '跟隨系統'],
   ['外观模式', '外觀模式'],
   ['登录系统后自动启动', '登入系統後自動啟動'],
diff --git a/src/styles.css b/src/styles.css
index dc4f42a..a73ac30 100644
--- a/src/styles.css
+++ b/src/styles.css
@@ -637,7 +637,7 @@ textarea:focus-visible {
 
 .sidebar-theme-selector {
   display: grid;
-  grid-template-columns: repeat(2, minmax(0, 1fr));
+  grid-template-columns: repeat(3, minmax(0, 1fr));
   gap: 3px;
   width: 100%;
   padding: 3px;
@@ -660,10 +660,6 @@ textarea:focus-visible {
   white-space: nowrap;
 }
 
-.sidebar-theme-selector button:last-child {
-  grid-column: 1 / -1;
-}
-
 .sidebar-theme-selector button:hover {
   background: var(--theme-e8e5dc);
   color: var(--theme-2d2a26);
diff --git a/tests/i18n.test.ts b/tests/i18n.test.ts
index ae24720..2f4c92d 100644
--- a/tests/i18n.test.ts
+++ b/tests/i18n.test.ts
@@ -5,12 +5,12 @@ import { jaOverrides } from '../src/i18n/ja';
 
 describe('i18n', () => {
   it('localizes system appearance controls in every language', () => {
-    expect(translate('zh-CN', 'app.theme.system')).toBe('跟随系统');
-    expect(translate('zh-TW', 'app.theme.system')).toBe('跟隨系統');
+    expect(translate('zh-CN', 'app.theme.system')).toBe('自动');
+    expect(translate('zh-TW', 'app.theme.system')).toBe('自動');
     expect(translate('zh-TW', 'app.theme.label')).toBe('外觀模式');
-    expect(translate('zh-TW', 'app.theme.switchToSystem')).toBe('隨系統自動切換日間和夜間模式');
-    expect(translate('en', 'app.theme.system')).toBe('Follow system');
-    expect(translate('ja', 'app.theme.system')).toBe('システムに従う');
+    expect(translate('zh-TW', 'app.theme.switchToSystem')).toBe('隨系統自動切換亮色和暗色');
+    expect(translate('en', 'app.theme.system')).toBe('Auto');
+    expect(translate('ja', 'app.theme.system')).toBe('自動');
   });
 
   it('uses credential-file terminology throughout both Chinese locales', () => {