diff --git a/src/Example/Program.cs b/src/Example/Program.cs
index ff453df..cb166b3 100644
--- a/src/Example/Program.cs
+++ b/src/Example/Program.cs
@@ -1,6 +1,7 @@
 using TinyTUI;
 using TinyTUI.Components;
 using TinyTUI.Input;
+using TinyTUI.Overlay;
 using TinyTUI.Rendering;
 using TinyTUI.Runtime;
 using TinyTUI.Stdio;
@@ -22,7 +23,16 @@ var input = new TinyTUI.Components.Input(textMeasurer) { Prompt = "请输入: "
 input.OnChanged = value => UpdateStatus(statusText, value, textMeasurer, renderer);
 input.OnSubmitted = value =>
 {
-    AddEvent(eventsText, $"Submitted: {value}");
+    if (value.Trim() == "/help")
+    {
+        AddEvent(eventsText, "Overlay: help opened");
+        runtime.ShowOverlay(new HelpOverlay(runtime, textMeasurer));
+    }
+    else
+    {
+        AddEvent(eventsText, $"Submitted: {value}");
+    }
+
     input.Clear();
 };
 input.OnCanceled = () => done.Set();
@@ -32,7 +42,7 @@ UpdateStatus(statusText, input.Value, textMeasurer, renderer);
 var page = new Container();
 page.Add(new Text("TinyTUI 基础组件示例"));
 page.Add(new Text("======================"));
-page.Add(new Text("测试方式: 输入文本 Backspace 删除 Enter 提交 Esc 退出"));
+page.Add(new Text("测试方式: 输入文本 Backspace 删除 Enter 提交 /help 打开弹层 Esc 退出"));
 page.Add(new Text(string.Empty));
 page.Add(new Box(statusText, textMeasurer) { Title = "状态" });
 page.Add(new Text(string.Empty));
@@ -78,3 +88,39 @@ static void AddEvent(Text eventsText, string message)
     var lines = eventsText.Value.Split('\n').Skip(1).Append($"- {message}").TakeLast(8);
     eventsText.Value = "最近事件:\n" + string.Join('\n', lines);
 }
+
+/// <summary>
+/// 用于手动验证 overlay 的帮助弹层
+/// </summary>
+file sealed class HelpOverlay(ITuiRuntime runtime, ITextMeasurer textMeasurer) : IInputComponent
+{
+    private readonly Box _box = new(
+        new Text(
+            "Overlay 示例\n" +
+            "\n" +
+            "这个弹层由 Runtime 显示\n" +
+            "OverlayManager 会把它合成到基础页面上\n" +
+            "显示时焦点会切到弹层\n" +
+            "关闭后焦点会恢复到输入框\n" +
+            "\n" +
+            "按 Enter 或 Esc 关闭"),
+        textMeasurer)
+    {
+        Title = "Help",
+    };
+
+    /// <inheritdoc />
+    public IReadOnlyList<string> Render(int width)
+    {
+        return _box.Render(width);
+    }
+
+    /// <inheritdoc />
+    public void HandleInput(TuiInputEvent input)
+    {
+        if (input is { Kind: TuiInputEventKind.Key, Value: KeyNames.Enter or KeyNames.Escape })
+        {
+            runtime.HideOverlay();
+        }
+    }
+}
diff --git a/src/TinyTUI/Components/Container.cs b/src/TinyTUI/Components/Container.cs
index 379737c..399c2ae 100644
--- a/src/TinyTUI/Components/Container.cs
+++ b/src/TinyTUI/Components/Container.cs
@@ -40,9 +40,7 @@ public class Container : IComponent
         var lines = new List<string>();
 
         foreach (var child in Children)
-        {
             lines.AddRange(child.Render(width));
-        }
 
         return lines;
     }
diff --git a/src/TinyTUI/Input/DefaultInputParser.cs b/src/TinyTUI/Input/DefaultInputParser.cs
index 207fb13..385b790 100644
--- a/src/TinyTUI/Input/DefaultInputParser.cs
+++ b/src/TinyTUI/Input/DefaultInputParser.cs
@@ -93,9 +93,7 @@ public sealed class DefaultInputParser : IInputParser
     private void ParseRegular(string data, List<TuiInputEvent> events)
     {
         if (data.Length == 0)
-        {
             return;
-        }
 
         if (_keyMap.TryGetValue(data, out var keyName))
         {
diff --git a/src/TinyTUI/Overlay/OverlayManager.cs b/src/TinyTUI/Overlay/OverlayManager.cs
new file mode 100644
index 0000000..7f554de
--- /dev/null
+++ b/src/TinyTUI/Overlay/OverlayManager.cs
@@ -0,0 +1,117 @@
+using TinyTUI.Components;
+using TinyTUI.Text;
+
+namespace TinyTUI.Overlay;
+
+/// <summary>
+/// 默认 overlay 管理器
+/// </summary>
+public sealed class OverlayManager(ITextMeasurer? textMeasurer = null) : IOverlayManager
+{
+    private readonly ITextMeasurer _textMeasurer = textMeasurer ?? new TerminalTextMeasurer();
+    private readonly List<OverlayEntry> _entries = [];
+
+    /// <summary>
+    /// 在 overlay 被移除时触发
+    /// </summary>
+    public event EventHandler<IComponent>? Removed;
+
+    /// <inheritdoc />
+    public bool HasOverlay => _entries.Any(static entry => !entry.Hidden);
+
+    /// <summary>
+    /// 获取最上层可见 overlay 组件
+    /// </summary>
+    public IComponent? TopVisibleComponent => _entries.LastOrDefault(static entry => !entry.Hidden)?.Component;
+
+    /// <inheritdoc />
+    public IOverlayHandle Show(IComponent component)
+    {
+        var entry = new OverlayEntry(component);
+        _entries.Add(entry);
+        return new OverlayHandle(entry, Remove, SetHidden);
+    }
+
+    /// <inheritdoc />
+    public void HideTop()
+    {
+        var top = _entries.LastOrDefault(static entry => !entry.Hidden);
+        if (top is not null) Remove(top);
+    }
+
+    /// <summary>
+    /// 将 overlay 合成到基础渲染行
+    /// </summary>
+    public IReadOnlyList<string> Compose(IReadOnlyList<string> baseLines, TerminalSize size)
+    {
+        var visibleEntries = _entries.Where(static entry => !entry.Hidden).ToArray();
+        if (visibleEntries.Length == 0)
+            return baseLines;
+
+        var result = baseLines.ToList();
+        while (result.Count < size.Rows)
+            result.Add(string.Empty);
+
+        foreach (var entry in visibleEntries)
+            ComposeOne(result, entry.Component, size);
+
+        return result;
+    }
+
+    private void ComposeOne(List<string> target, IComponent component, TerminalSize size)
+    {
+        var overlayWidth = Math.Clamp(Math.Min(60, size.Columns - 4), 1, Math.Max(1, size.Columns));
+        var overlayLines = component.Render(overlayWidth).Select(line => _textMeasurer.Truncate(line, overlayWidth)).ToArray();
+        var overlayHeight = overlayLines.Length;
+        var row = Math.Max(0, (size.Rows - overlayHeight) / 2);
+        var column = Math.Max(0, (size.Columns - overlayWidth) / 2);
+
+        while (target.Count < row + overlayHeight)
+            target.Add(string.Empty);
+
+        for (var index = 0; index < overlayLines.Length; index++)
+            target[row + index] = ComposeLine(target[row + index], overlayLines[index], column, overlayWidth, size.Columns);
+    }
+
+    private string ComposeLine(string baseLine, string overlayLine, int column, int overlayWidth, int totalWidth)
+    {
+        var before = _textMeasurer.Truncate(baseLine, column);
+        var beforePadding = Math.Max(0, column - _textMeasurer.GetWidth(before));
+        var overlayPadding = Math.Max(0, overlayWidth - _textMeasurer.GetWidth(overlayLine));
+        var afterStartWidth = column + overlayWidth;
+        var after = _textMeasurer.GetWidth(baseLine) > afterStartWidth ? string.Empty : string.Empty;
+        var merged = before + new string(' ', beforePadding) + overlayLine + new string(' ', overlayPadding) + after;
+        return _textMeasurer.Truncate(merged, totalWidth);
+    }
+
+    private void SetHidden(OverlayEntry entry, bool hidden)
+    {
+        if (!_entries.Contains(entry)) return;
+
+        entry.Hidden = hidden;
+    }
+
+    private void Remove(OverlayEntry entry)
+    {
+        if (!_entries.Remove(entry)) return;
+
+        Removed?.Invoke(this, entry.Component);
+    }
+
+    private sealed class OverlayEntry(IComponent component)
+    {
+        public IComponent Component { get; } = component;
+
+        public bool Hidden { get; set; }
+    }
+
+    private sealed class OverlayHandle(
+        OverlayEntry entry,
+        Action<OverlayEntry> hide,
+        Action<OverlayEntry, bool> setHidden) : IOverlayHandle
+    {
+        public void Hide() => hide(entry);
+
+        public void SetHidden(bool hidden) => setHidden(entry, hidden);
+    }
+}
diff --git a/src/TinyTUI/Rendering/DifferentialRenderer.cs b/src/TinyTUI/Rendering/DifferentialRenderer.cs
index 296dde1..03259a7 100644
--- a/src/TinyTUI/Rendering/DifferentialRenderer.cs
+++ b/src/TinyTUI/Rendering/DifferentialRenderer.cs
@@ -73,32 +73,20 @@ public sealed class DifferentialRenderer(ITerminalOutput output, ITextMeasurer?
             var previous = index < _previousLines.Count ? _previousLines[index] : string.Empty;
             var next = index < lines.Count ? lines[index] : string.Empty;
 
-            if (previous == next)
-            {
-                continue;
-            }
+            if (previous == next) continue;
 
             changed = true;
             output.Write($"\e[{index + 1};1H");
             output.Write("\e[2K");
 
-            if (next.Length > 0)
-            {
-                output.Write(next);
-            }
+            if (next.Length > 0) output.Write(next);
         }
 
-        if (cursor is not null)
-        {
-            MoveCursor(cursor);
-        }
+        if (cursor is not null) MoveCursor(cursor);
 
         if (changed || cursor is not null)
         {
-            if (changed)
-            {
-                DifferentialRedrawCount++;
-            }
+            if (changed) DifferentialRedrawCount++;
 
             output.Flush();
         }
@@ -108,15 +96,10 @@ public sealed class DifferentialRenderer(ITerminalOutput output, ITextMeasurer?
     }
 
     private List<string> NormalizeLines(IReadOnlyList<string> lines, int width)
-    {
-        return [.. lines.Select(line => _textMeasurer.Truncate(line, width))];
-    }
+        => [.. lines.Select(line => _textMeasurer.Truncate(line, width))];
 
     private void MoveCursor(CursorPosition? cursor)
     {
-        if (cursor is { } position)
-        {
-            output.MoveCursorTo(position.Row, position.Column);
-        }
+        if (cursor is { } position) output.MoveCursorTo(position.Row, position.Column);
     }
 }
diff --git a/src/TinyTUI/Rendering/FullScreenRenderer.cs b/src/TinyTUI/Rendering/FullScreenRenderer.cs
index 2431a62..0d6dac1 100644
--- a/src/TinyTUI/Rendering/FullScreenRenderer.cs
+++ b/src/TinyTUI/Rendering/FullScreenRenderer.cs
@@ -36,9 +36,7 @@ public sealed class FullScreenRenderer(ITerminalOutput output, ITextMeasurer? te
     }
 
     private List<string> NormalizeLines(IReadOnlyList<string> lines, int width)
-    {
-        return [.. lines.Select(line => _textMeasurer.Truncate(line, width))];
-    }
+        => [.. lines.Select(line => _textMeasurer.Truncate(line, width))];
 
     private void MoveCursor(CursorPosition? cursor)
     {
diff --git a/src/TinyTUI/Runtime/ITuiRuntime.cs b/src/TinyTUI/Runtime/ITuiRuntime.cs
index 1f6fa3c..9317fd7 100644
--- a/src/TinyTUI/Runtime/ITuiRuntime.cs
+++ b/src/TinyTUI/Runtime/ITuiRuntime.cs
@@ -1,4 +1,5 @@
 using TinyTUI.Components;
+using TinyTUI.Overlay;
 
 namespace TinyTUI.Runtime;
 
@@ -27,6 +28,16 @@ public interface ITuiRuntime : IDisposable
     /// </summary>
     void RequestRender();
 
+    /// <summary>
+    /// 显示 overlay 组件并切换焦点
+    /// </summary>
+    IOverlayHandle ShowOverlay(IComponent component);
+
+    /// <summary>
+    /// 隐藏最上层 overlay
+    /// </summary>
+    void HideOverlay();
+
     /// <summary>
     /// 启动 TUI 运行时
     /// </summary>
diff --git a/src/TinyTUI/Runtime/TuiRuntime.cs b/src/TinyTUI/Runtime/TuiRuntime.cs
index 3dc8261..7e6529a 100644
--- a/src/TinyTUI/Runtime/TuiRuntime.cs
+++ b/src/TinyTUI/Runtime/TuiRuntime.cs
@@ -1,5 +1,6 @@
 using TinyTUI.Components;
 using TinyTUI.Input;
+using TinyTUI.Overlay;
 using TinyTUI.Rendering;
 using TinyTUI.Stdio;
 
@@ -13,8 +14,10 @@ public sealed class TuiRuntime : ITuiRuntime
     private readonly ITerminalInput _terminalInput;
     private readonly IInputParser _inputParser;
     private readonly IRenderer _renderer;
+    private readonly OverlayManager _overlayManager = new();
     private readonly Container _root = new();
     private readonly Lock _renderLock = new();
+    private readonly Dictionary<IComponent, IComponent?> _overlayFocusRestore = [];
 
     private IComponent? _focusedComponent;
     private bool _started;
@@ -27,6 +30,7 @@ public sealed class TuiRuntime : ITuiRuntime
         _terminalInput = terminalInput;
         _inputParser = inputParser;
         _renderer = renderer;
+        _overlayManager.Removed += OnOverlayRemoved;
     }
 
     /// <inheritdoc />
@@ -41,43 +45,45 @@ public sealed class TuiRuntime : ITuiRuntime
     {
         _root.Remove(component);
 
-        if (_focusedComponent == component)
-        {
-            _focusedComponent = null;
-        }
+        if (_focusedComponent == component) _focusedComponent = null;
 
         RequestRender();
     }
 
     /// <inheritdoc />
-    public void SetFocus(IComponent? component)
-    {
-        _focusedComponent = component;
-    }
+    public void SetFocus(IComponent? component) => _focusedComponent = component;
 
     /// <inheritdoc />
     public void RequestRender()
     {
-        if (!_started)
-        {
-            return;
-        }
+        if (!_started) return;
 
         lock (_renderLock)
         {
             var size = _terminalInput.CurrentSize;
             var lines = _root.Render(size.Columns);
+            lines = [.. _overlayManager.Compose(lines, size)];
             _renderer.Render(lines, size);
         }
     }
 
+    /// <inheritdoc />
+    public IOverlayHandle ShowOverlay(IComponent component)
+    {
+        _overlayFocusRestore[component] = _focusedComponent;
+        var handle = _overlayManager.Show(component);
+        SetFocus(component);
+        RequestRender();
+        return handle;
+    }
+
+    /// <inheritdoc />
+    public void HideOverlay() => _overlayManager.HideTop();
+
     /// <inheritdoc />
     public void Start()
     {
-        if (_started)
-        {
-            return;
-        }
+        if (_started) return;
 
         _started = true;
         _terminalInput.DataReceived += OnDataReceived;
@@ -90,10 +96,7 @@ public sealed class TuiRuntime : ITuiRuntime
     /// <inheritdoc />
     public void Stop()
     {
-        if (!_started)
-        {
-            return;
-        }
+        if (!_started) return;
 
         _started = false;
         _terminalInput.DataReceived -= OnDataReceived;
@@ -111,22 +114,26 @@ public sealed class TuiRuntime : ITuiRuntime
     private void OnDataReceived(object? sender, string data)
     {
         foreach (var inputEvent in _inputParser.Parse(data))
-        {
             Dispatch(inputEvent);
-        }
     }
 
     private void OnResized(object? sender, TerminalSize size)
-    {
-        Dispatch(new TuiInputEvent(TuiInputEventKind.Resize, $"{size.Columns}x{size.Rows}"));
-    }
+        => Dispatch(new TuiInputEvent(TuiInputEventKind.Resize, $"{size.Columns}x{size.Rows}"));
 
     private void Dispatch(TuiInputEvent inputEvent)
     {
         if (_focusedComponent is IInputComponent inputComponent)
-        {
             inputComponent.HandleInput(inputEvent);
-        }
+
+        RequestRender();
+    }
+
+    private void OnOverlayRemoved(object? sender, IComponent component)
+    {
+        _overlayFocusRestore.Remove(component, out var restoreFocus);
+
+        if (_focusedComponent == component)
+            _focusedComponent = _overlayManager.TopVisibleComponent ?? restoreFocus;
 
         RequestRender();
     }
diff --git a/src/TinyTUI/Stdio/ConsoleTerminalInput.cs b/src/TinyTUI/Stdio/ConsoleTerminalInput.cs
index d1acc72..6f43b6c 100644
--- a/src/TinyTUI/Stdio/ConsoleTerminalInput.cs
+++ b/src/TinyTUI/Stdio/ConsoleTerminalInput.cs
@@ -24,10 +24,7 @@ public sealed class ConsoleTerminalInput : ITerminalInput
     /// <inheritdoc />
     public void Start()
     {
-        if (_cancellation is not null)
-        {
-            return;
-        }
+        if (_cancellation is not null) return;
 
         _previousTreatControlCAsInput = Console.TreatControlCAsInput;
         Console.TreatControlCAsInput = true;
@@ -41,10 +38,7 @@ public sealed class ConsoleTerminalInput : ITerminalInput
     public void Stop()
     {
         var cancellation = _cancellation;
-        if (cancellation is null)
-        {
-            return;
-        }
+        if (cancellation is null) return;
 
         cancellation.Cancel();
 
diff --git a/src/TinyTUI/Stdout/ConsoleTerminalOutput.cs b/src/TinyTUI/Stdout/ConsoleTerminalOutput.cs
index 13d4262..6a1caf0 100644
--- a/src/TinyTUI/Stdout/ConsoleTerminalOutput.cs
+++ b/src/TinyTUI/Stdout/ConsoleTerminalOutput.cs
@@ -17,53 +17,30 @@ public sealed class ConsoleTerminalOutput : ITerminalOutput
     /// <summary>
     /// 创建使用指定 TextWriter 的终端输出实现
     /// </summary>
-    public ConsoleTerminalOutput(TextWriter writer)
-    {
-        _writer = writer;
-    }
+    public ConsoleTerminalOutput(TextWriter writer) => _writer = writer;
 
     /// <inheritdoc />
-    public void Write(string value)
-    {
-        _writer.Write(value);
-    }
+    public void Write(string value) => _writer.Write(value);
 
     /// <inheritdoc />
-    public void Flush()
-    {
-        _writer.Flush();
-    }
+    public void Flush() => _writer.Flush();
 
     /// <inheritdoc />
-    public void ClearScreen()
-    {
-        Write("\x1b[2J\x1b[H");
-    }
+    public void ClearScreen() => Write("\e[2J\e[H");
 
     /// <inheritdoc />
-    public void HideCursor()
-    {
-        Write("\x1b[?25l");
-    }
+    public void HideCursor() => Write("\e[?25l");
 
     /// <inheritdoc />
-    public void ShowCursor()
-    {
-        Write("\x1b[?25h");
-    }
+    public void ShowCursor() => Write("\e[?25h");
 
     /// <inheritdoc />
-    public void MoveCursorTo(int row, int column)
-    {
-        Write($"\e[{row};{column}H");
-    }
+    public void MoveCursorTo(int row, int column) => Write($"\e[{row};{column}H");
 
     private static TextWriter CreateConsoleWriter()
     {
         if (!Console.IsOutputRedirected)
-        {
             Console.OutputEncoding = Encoding.UTF8;
-        }
 
         return Console.Out;
     }
diff --git a/src/TinyTUI/Text/TerminalTextMeasurer.cs b/src/TinyTUI/Text/TerminalTextMeasurer.cs
index fe88c11..507de52 100644
--- a/src/TinyTUI/Text/TerminalTextMeasurer.cs
+++ b/src/TinyTUI/Text/TerminalTextMeasurer.cs
@@ -40,9 +40,7 @@ public sealed class TerminalTextMeasurer : ITextMeasurer
     public string Truncate(string value, int maxWidth)
     {
         if (maxWidth <= 0)
-        {
             return string.Empty;
-        }
 
         var builder = new StringBuilder();
         var width = 0;