diff --git a/src/ui/FramelessDelegateWin.cpp b/src/ui/FramelessDelegateWin.cpp
index 26c1cb75..96d822b7 100644
--- a/src/ui/FramelessDelegateWin.cpp
+++ b/src/ui/FramelessDelegateWin.cpp
@@ -27,7 +27,8 @@ namespace Gdiplus
 #pragma comment (lib,"Dwmapi.lib") // Adds missing library, fixes error LNK2019: unresolved external symbol __imp__DwmExtendFrameIntoClientArea
 #pragma comment (lib,"user32.lib")
 
-constexpr unsigned long BorderlessFlag = WS_POPUP | WS_THICKFRAME | WS_CAPTION | WS_SYSMENU | WS_MAXIMIZEBOX | WS_MINIMIZEBOX;
+// 无边框样式：不使用 CAPTION 与系统按钮，避免在 Win7 显示原生按钮
+constexpr unsigned long BorderlessFlag = WS_POPUP | WS_THICKFRAME | WS_SYSMENU;
 
 inline bool IsCompositionEnabled() {
 #if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
@@ -102,8 +103,11 @@ bool FramelessDelegateWin::nativeEvent(const QByteArray & eventType, void* messa
                     return true;
                 }
                 NCCALCSIZE_PARAMS* ncParam = reinterpret_cast<NCCALCSIZE_PARAMS*>(msg->lParam);
+                // 最大化时将客户区严格对齐到工作区，避免左右空隙
+                ncParam->rgrc[0].left = rc->left();
                 ncParam->rgrc[0].top = rc->top();
-                ncParam->rgrc[0].bottom = rc->bottom() + 1;
+                ncParam->rgrc[0].right = rc->right();
+                ncParam->rgrc[0].bottom = rc->bottom();
                 *result = 0;
                 return true;
             } else {
@@ -165,15 +169,13 @@ bool FramelessDelegateWin::nativeEvent(const QByteArray & eventType, void* messa
             AdjustWindowRectEx(&frame, WS_OVERLAPPEDWINDOW, FALSE, 0);
             double dpr = mainWidget_->devicePixelRatioF();
 
-            frames_.setLeft(abs(frame.left) / dpr + 0.5);
-            frames_.setTop(abs(frame.bottom) / dpr + 0.5);
-            frames_.setRight(abs(frame.right) / dpr + 0.5);
-            frames_.setBottom(abs(frame.bottom) / dpr + 0.5);
+            // 最大化时不叠加系统边框内边距，避免左右出现可见空隙
+            frames_.setLeft(0);
+            frames_.setTop(0);
+            frames_.setRight(0);
+            frames_.setBottom(0);
 
-            mainWidget_->setContentsMargins(frames_.left() + margins_.left(), \
-                frames_.top() + margins_.top(), \
-                frames_.right() + margins_.right(), \
-                frames_.bottom() + margins_.bottom());
+            mainWidget_->setContentsMargins(margins_);
             justMaximized_ = true;
         } else {
             if (justMaximized_) {
@@ -361,6 +363,11 @@ void FramelessDelegateWin::SetNativeWindowLong() {
     // 避免父窗口与子窗口重叠绘制导致闪烁，启用剪裁样式
     style |= WS_CLIPCHILDREN | WS_CLIPSIBLINGS;
 
+    // 显式清理可能由 Qt 或系统设置的标题栏与系统按钮标志，确保不显示原生按钮
+    style &= ~WS_CAPTION;
+    style &= ~WS_MINIMIZEBOX;
+    style &= ~WS_MAXIMIZEBOX;
+
     if (!mainWidget_->windowFlags().testFlag(Qt::WindowMinimizeButtonHint) ||
         mainWidget_->maximumSize() != QSize(QWIDGETSIZE_MAX, QWIDGETSIZE_MAX)) {
         style &= ~WS_MINIMIZEBOX;