diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8cdc954..d9ed53c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## 4.9.18 - 2026-07-29
+
+- 修复移动端播放器控制栏在窄屏下被裁切、最右侧“系统全屏”按钮不可见的问题（#224）。
+- 控制栏现在根据播放器自身宽度进入紧凑布局：隐藏窄屏音量入口、压缩间距，并在极窄播放器中只显示当前播放时间；画中画、AirPlay、Cast、网页全屏与系统全屏按钮继续保留。
+- 新增移动端播放器控制栏回归测试，锁定两个全屏入口在窄屏下不会再次被可选播放按钮挤出可视区。
+
 ## 4.9.17 - 2026-07-29
 
 - 新增基于主内容时长残差的组合式 M3U8 插播检测；残差只作为辅助证据，单个 `.033/.333/.867` 等合法分片不再被直接删除。
diff --git a/app-release.json b/app-release.json
index 19e40b1..5a6b90d 100644
--- a/app-release.json
+++ b/app-release.json
@@ -4,8 +4,18 @@
     "name": "KVideo",
     "branch": "main"
   },
-  "currentVersion": "4.9.17",
+  "currentVersion": "4.9.18",
   "releases": [
+    {
+      "version": "4.9.18",
+      "publishedAt": "2026-07-29",
+      "title": "修复移动端系统全屏按钮",
+      "notes": [
+        "修复移动端播放器控制栏在窄屏下被裁切、最右侧系统全屏按钮不可见的问题（#224）。",
+        "控制栏按播放器自身宽度切换紧凑布局，窄屏隐藏音量入口并压缩间距，极窄播放器只显示当前播放时间。",
+        "画中画、AirPlay、Cast、网页全屏与系统全屏按钮全部保留，并新增响应式控制栏回归测试。"
+      ]
+    },
     {
       "version": "4.9.17",
       "publishedAt": "2026-07-29",
diff --git a/app/styles/video-player.css b/app/styles/video-player.css
index 16e5db2..c66958b 100644
--- a/app/styles/video-player.css
+++ b/app/styles/video-player.css
@@ -1,4 +1,8 @@
 /* Video Player Components */
+.kvideo-container {
+    container-type: inline-size;
+}
+
 .spinner {
     width: 48px;
     height: 48px;
@@ -435,3 +439,54 @@
     cursor: pointer;
     touch-action: manipulation;
 }
+
+/*
+ * Keep fullscreen actions visible when the player itself becomes narrow.
+ * Container queries are used instead of viewport queries because the player
+ * can also be narrow inside the desktop player/sidebar grid.
+ */
+@container (max-width: 36rem) {
+    .kvideo-container .player-controls-bar {
+        padding: 0.5rem;
+    }
+
+    .kvideo-container .player-controls-row {
+        gap: 0.25rem;
+    }
+
+    .kvideo-container .player-controls-left {
+        gap: 0.375rem;
+    }
+
+    .kvideo-container .player-volume-control {
+        display: none;
+    }
+
+    .kvideo-container .player-controls-right {
+        flex: 0 0 auto;
+        gap: 0.25rem;
+    }
+
+    .kvideo-container .player-time-display {
+        flex: 1 1 auto;
+        overflow: hidden;
+        text-overflow: ellipsis;
+        white-space: nowrap;
+        font-size: 0.75rem;
+    }
+}
+
+@container (max-width: 24rem) {
+    .kvideo-container .player-controls-row {
+        gap: 0.125rem;
+    }
+
+    .kvideo-container .player-controls-left,
+    .kvideo-container .player-controls-right {
+        gap: 0.25rem;
+    }
+
+    .kvideo-container .player-duration-display {
+        display: none;
+    }
+}
diff --git a/components/player/desktop/DesktopControls.tsx b/components/player/desktop/DesktopControls.tsx
index 3ffb46a..1474e57 100644
--- a/components/player/desktop/DesktopControls.tsx
+++ b/components/player/desktop/DesktopControls.tsx
@@ -73,8 +73,8 @@ export function DesktopControls(props: DesktopControlsProps) {
             />
 
             {/* Controls Bar */}
-            <div className="bg-gradient-to-t from-black/90 via-black/70 to-transparent px-4 pb-4 pt-2">
-                <div className="flex items-center justify-between gap-4">
+            <div className="player-controls-bar bg-gradient-to-t from-black/90 via-black/70 to-transparent px-4 pb-4 pt-2">
+                <div className="player-controls-row flex min-w-0 items-center justify-between gap-4">
                     <DesktopLeftControls {...props} formatTime={formatTime} />
                     <DesktopRightControls {...props} />
                 </div>
diff --git a/components/player/desktop/DesktopLeftControls.tsx b/components/player/desktop/DesktopLeftControls.tsx
index f545e4c..ffd670b 100644
--- a/components/player/desktop/DesktopLeftControls.tsx
+++ b/components/player/desktop/DesktopLeftControls.tsx
@@ -32,30 +32,33 @@ export function DesktopLeftControls({
     formatTime
 }: DesktopLeftControlsProps) {
     return (
-        <div className="flex items-center gap-3">
+        <div className="player-controls-left flex min-w-0 flex-1 items-center gap-3">
             {/* Play/Pause */}
             <button
                 onClick={onTogglePlay}
-                className="btn-icon"
+                className="btn-icon shrink-0"
                 aria-label={isPlaying ? 'Pause' : 'Play'}
             >
                 {isPlaying ? <Icons.Pause size={20} /> : <Icons.Play size={20} />}
             </button>
 
             {/* Volume */}
-            <DesktopVolumeControl
-                volumeBarRef={volumeBarRef}
-                volume={volume}
-                isMuted={isMuted}
-                showVolumeBar={showVolumeBar}
-                onToggleMute={onToggleMute}
-                onVolumeChange={onVolumeChange}
-                onVolumeMouseDown={onVolumeMouseDown}
-            />
+            <div className="player-volume-control shrink-0">
+                <DesktopVolumeControl
+                    volumeBarRef={volumeBarRef}
+                    volume={volume}
+                    isMuted={isMuted}
+                    showVolumeBar={showVolumeBar}
+                    onToggleMute={onToggleMute}
+                    onVolumeChange={onVolumeChange}
+                    onVolumeMouseDown={onVolumeMouseDown}
+                />
+            </div>
 
             {/* Time */}
-            <span className="text-white text-sm font-medium tabular-nums">
-                {formatTime(currentTime)} / {formatTime(duration)}
+            <span className="player-time-display min-w-0 truncate text-sm font-medium text-white tabular-nums">
+                <span>{formatTime(currentTime)}</span>
+                <span className="player-duration-display"> / {formatTime(duration)}</span>
             </span>
         </div>
     );
diff --git a/components/player/desktop/DesktopRightControls.tsx b/components/player/desktop/DesktopRightControls.tsx
index 4037227..9e1d37f 100644
--- a/components/player/desktop/DesktopRightControls.tsx
+++ b/components/player/desktop/DesktopRightControls.tsx
@@ -29,13 +29,13 @@ export function DesktopRightControls({
     onShowCastMenu
 }: DesktopRightControlsProps) {
     return (
-        <div className="relative z-50 flex items-center gap-3">
+        <div className="player-controls-right relative z-50 flex shrink-0 items-center gap-3">
             {/* Picture-in-Picture */}
             {
                 isPiPSupported && (
                     <button
                         onClick={onTogglePictureInPicture}
-                        className="btn-icon"
+                        className="btn-icon shrink-0"
                         aria-label="画中画"
                         title="画中画"
                     >
@@ -49,7 +49,7 @@ export function DesktopRightControls({
                 isAirPlaySupported && (
                     <button
                         onClick={onShowAirPlayMenu}
-                        className="btn-icon"
+                        className="btn-icon shrink-0"
                         aria-label="隔空播放"
                         title="隔空播放"
                     >
@@ -63,7 +63,7 @@ export function DesktopRightControls({
                 isCastAvailable && (
                     <button
                         onClick={onShowCastMenu}
-                        className="btn-icon"
+                        className="btn-icon shrink-0"
                         aria-label="投屏"
                         title="投屏"
                     >
@@ -75,7 +75,7 @@ export function DesktopRightControls({
             {/* Web Fullscreen */}
             <button
                 onClick={onToggleWebFullscreen}
-                className="btn-icon"
+                className="btn-icon shrink-0"
                 aria-label={isWebFullscreen ? '退出网页全屏' : '网页全屏'}
                 title={isWebFullscreen ? '退出网页全屏 (W)' : '网页全屏 (W)'}
             >
@@ -87,7 +87,7 @@ export function DesktopRightControls({
             {/* Native Fullscreen */}
             <button
                 onClick={onToggleNativeFullscreen}
-                className="btn-icon"
+                className="btn-icon shrink-0"
                 aria-label={isNativeFullscreen ? '退出系统全屏' : '系统全屏'}
                 title={isNativeFullscreen ? '退出系统全屏 (F)' : '系统全屏 (F)'}
             >
diff --git a/package-lock.json b/package-lock.json
index 3021cc4..174dc86 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "kvideo",
-  "version": "4.9.17",
+  "version": "4.9.18",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "kvideo",
-      "version": "4.9.17",
+      "version": "4.9.18",
       "dependencies": {
         "@dnd-kit/core": "^6.3.1",
         "@dnd-kit/sortable": "^10.0.0",
diff --git a/package.json b/package.json
index 9c732eb..6f7b193 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "kvideo",
-  "version": "4.9.17",
+  "version": "4.9.18",
   "private": true,
   "scripts": {
     "dev": "node scripts/next-with-lan-access.mjs dev",
diff --git a/tests/mobile-player-controls.test.ts b/tests/mobile-player-controls.test.ts
new file mode 100644
index 0000000..3d70020
--- /dev/null
+++ b/tests/mobile-player-controls.test.ts
@@ -0,0 +1,38 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { readFileSync } from 'node:fs';
+import { join } from 'node:path';
+
+const projectRoot = process.cwd();
+
+test('narrow player controls reserve space for both fullscreen actions', () => {
+  const controls = readFileSync(
+    join(projectRoot, 'components/player/desktop/DesktopControls.tsx'),
+    'utf8',
+  );
+  const leftControls = readFileSync(
+    join(projectRoot, 'components/player/desktop/DesktopLeftControls.tsx'),
+    'utf8',
+  );
+  const rightControls = readFileSync(
+    join(projectRoot, 'components/player/desktop/DesktopRightControls.tsx'),
+    'utf8',
+  );
+  const styles = readFileSync(
+    join(projectRoot, 'app/styles/video-player.css'),
+    'utf8',
+  );
+
+  assert.match(controls, /player-controls-row flex min-w-0/);
+  assert.match(leftControls, /player-controls-left flex min-w-0 flex-1/);
+  assert.match(leftControls, /player-volume-control/);
+  assert.match(leftControls, /player-duration-display/);
+  assert.match(rightControls, /player-controls-right[^\n]*shrink-0/);
+  assert.match(rightControls, /onClick=\{onToggleWebFullscreen\}/);
+  assert.match(rightControls, /onClick=\{onToggleNativeFullscreen\}/);
+
+  assert.match(styles, /\.kvideo-container\s*\{\s*container-type:\s*inline-size;/);
+  assert.match(styles, /@container \(max-width: 36rem\)[\s\S]*?\.player-volume-control\s*\{\s*display:\s*none;/);
+  assert.match(styles, /@container \(max-width: 36rem\)[\s\S]*?\.player-controls-right\s*\{[\s\S]*?flex:\s*0 0 auto;/);
+  assert.match(styles, /@container \(max-width: 24rem\)[\s\S]*?\.player-duration-display\s*\{\s*display:\s*none;/);
+});