diff --git a/UEFITool/uefitool.cpp b/UEFITool/uefitool.cpp
index 0722816..f38a845 100644
--- a/UEFITool/uefitool.cpp
+++ b/UEFITool/uefitool.cpp
@@ -148,7 +148,7 @@ void UEFITool::init()
     model->setMarkingEnabled(markingEnabled);
     ui->actionToggleBootGuardMarking->setChecked(markingEnabled);
     
-    // Connect
+    // Connect signals to slots
     connect(ui->structureTreeView->selectionModel(), SIGNAL(currentChanged(const QModelIndex &, const QModelIndex &)),
             this, SLOT(populateUi(const QModelIndex &)));
     connect(ui->structureTreeView->selectionModel(), SIGNAL(selectionChanged(const QItemSelection &, const QItemSelection &)),
@@ -162,10 +162,17 @@ void UEFITool::init()
     connect(ui->fitTableWidget, SIGNAL(itemDoubleClicked(QTableWidgetItem*)), this, SLOT(scrollTreeView(QTableWidgetItem*)));
     connect(ui->messagesTabWidget, SIGNAL(currentChanged(int)), this, SLOT(currentTabChanged(int)));
     
-    // allow enter/return pressing to scroll tree view
+    // Allow enter/return pressing to scroll tree view
     ui->parserMessagesListWidget->installEventFilter(this);
     ui->finderMessagesListWidget->installEventFilter(this);
     ui->builderMessagesListWidget->installEventFilter(this);
+
+    // Switch default window style to Fusion on Qt6 Windows builds
+    // TOOD: remove this one default style gains dark theme support
+#if defined Q_OS_WIN and QT_VERSION_MAJOR >= 6
+    QApplication::setStyle(QStyleFactory::create("Fusion"));
+    QApplication::setPalette(QApplication::style()->standardPalette());
+#endif
 }
 
 void UEFITool::populateUi(const QItemSelection &selected)
diff --git a/UEFITool/uefitool.h b/UEFITool/uefitool.h
index d758ba6..7c68ab0 100644
--- a/UEFITool/uefitool.h
+++ b/UEFITool/uefitool.h
@@ -31,6 +31,7 @@
 #include <QProcess>
 #include <QSettings>
 #include <QSplitter>
+#include <QStyleFactory>
 #include <QString>
 #include <QTableWidget>
 #include <QTreeView>
diff --git a/common/ffsparser.cpp b/common/ffsparser.cpp
index 588469b..95dd684 100644
--- a/common/ffsparser.cpp
+++ b/common/ffsparser.cpp
@@ -35,17 +35,6 @@
 #include "digest/sha2.h"
 #include "digest/sm3.h"
 
-#ifndef QT_CORE_LIB
-namespace Qt {
-enum GlobalColor {
-    red = 7,
-    green = 8,
-    cyan = 10,
-    yellow = 12,
-};
-}
-#endif
-
 // Constructor
 FfsParser::FfsParser(TreeModel* treeModel) : model(treeModel),
 imageBase(0), addressDiff(0x100000000ULL), protectedRegionsBase(0) {
@@ -3778,14 +3767,14 @@ USTATUS FfsParser::markProtectedRangeRecursive(const UModelIndex & index, const
         if (std::min(currentOffset + currentSize, range.Offset + range.Size) > std::max(currentOffset, range.Offset)) {
             if (range.Offset <= currentOffset && currentOffset + currentSize <= range.Offset + range.Size) { // Mark as fully in range
                 if (range.Type == PROTECTED_RANGE_INTEL_BOOT_GUARD_IBB) {
-                    model->setMarking(index, Qt::red);
+                    model->setMarking(index, BootGuardMarking::BootGuardFullyInRange);
                 }
                 else {
-                    model->setMarking(index, Qt::cyan);
+                    model->setMarking(index, BootGuardMarking::VendorFullyInRange);
                 }
             }
             else { // Mark as partially in range
-                model->setMarking(index, Qt::yellow);
+                model->setMarking(index, BootGuardMarking::PartiallyInRange);
             }
         }
     }
diff --git a/common/treemodel.cpp b/common/treemodel.cpp
index b49c508..0ae747d 100644
--- a/common/treemodel.cpp
+++ b/common/treemodel.cpp
@@ -28,8 +28,17 @@ QVariant TreeModel::data(const UModelIndex &index, int role) const
     }
 #if defined (QT_GUI_LIB)
     else if (role == Qt::BackgroundRole) {
-        if (markingEnabledFlag && marking(index) > 0) {
-            return QBrush((Qt::GlobalColor)marking(index));
+        if (markingEnabledFlag && marking(index) != BootGuardMarking::None) {
+            // Use light colors by default
+            uint8_t bgFullyInRange = Qt::red;
+            uint8_t vendorFullyInRange = Qt::cyan;
+            uint8_t partiallyInRange = Qt::yellow;
+
+            switch (marking(index)) {
+                case BootGuardMarking::BootGuardFullyInRange: return QBrush((Qt::GlobalColor)bgFullyInRange); break;
+                case BootGuardMarking::VendorFullyInRange: return QBrush((Qt::GlobalColor)vendorFullyInRange); break;
+                case BootGuardMarking::PartiallyInRange: return QBrush((Qt::GlobalColor)partiallyInRange); break;
+            }
         }
     }
 #endif
diff --git a/common/treemodel.h b/common/treemodel.h
index 7ff4c8c..50fbfc7 100644
--- a/common/treemodel.h
+++ b/common/treemodel.h
@@ -19,6 +19,13 @@ enum ItemFixedState {
     Fixed
 };
 
+enum BootGuardMarking {
+    None = 0, // Needs to be zero
+    PartiallyInRange,
+    BootGuardFullyInRange,
+    VendorFullyInRange
+};
+
 #if defined(QT_CORE_LIB)
 // Use Qt classes
 #include <QAbstractItemModel>