diff --git a/docs/steamframe/DESIGN.md b/docs/steamframe/DESIGN.md
index a811814..dfd9a40 100644
--- a/docs/steamframe/DESIGN.md
+++ b/docs/steamframe/DESIGN.md
@@ -281,6 +281,30 @@ suspect; measuring needs the unwarped rendered image.
 - `run.sh`: arguments after the graphics API go to the program
   (`./run.sh opengl --snapshot /tmp/ovras.png`).
 
+## 11. Quick Controls style: Fusion, no Material import (approved 2026-10-08)
+
+**Finding (measured with `--snapshot`, DESIGN.md section 10):** the font is as intended (20 pt
+= 27 px, 96 DPI, device pixel ratio 1). The controls run in the Material style: `qt6`
+(`93c0851`) changed `mainwidget.qml`'s `import QtQuick.Controls` into
+`import QtQuick.Controls.Material`. That import fixes Material for all controls and even
+overrides `QT_QUICK_CONTROLS_STYLE`. Material's insets and padding make the navigation
+buttons 65 px tall (75 px pitch), so the fixed 1200×800 root page loses about its bottom
+quarter. Nothing in the file uses Material.
+
+| Style (root page, navigation buttons) | Button | Pitch | Result |
+|---|---|---|---|
+| Material (`qt6` as is) | 65 px | 75 px | 9 of 12 buttons visible |
+| Basic (Qt 5's "Default" renamed) | 49 px | 59 px | last button cut off (18 of 49 px) |
+| Fusion (Qt 6's Linux default) | 45 px | 55 px | everything fits |
+
+**Changes:**
+- `mainwidget.qml`: `import QtQuick.Controls` again, as before `93c0851`, with a comment.
+- `main.cpp`: `QQuickStyle::setStyle("Fusion")` after `QQuickWindow::setGraphicsApi()`,
+  before any QML is loaded. Explicit, so the look and sizes are the same on every platform
+  (without it Qt 6 picks Windows' own style there). Links `Qt6QuickControls2` directly
+  (already a dependency; present on the Frame: `/usr/lib/libQt6QuickControls2.so.6.8.0`).
+- Upstream note: with Material, the layout overflows on Windows too.
+
 ## Tests
 
 - **x86_64 locally:** the build succeeds; `objdump` check (R1).
diff --git a/docs/steamframe/PROGRESS.md b/docs/steamframe/PROGRESS.md
index 05a456a..532c64d 100644
--- a/docs/steamframe/PROGRESS.md
+++ b/docs/steamframe/PROGRESS.md
@@ -288,6 +288,27 @@ URL: "steam://launch/1009850/openvroverlay" auto-launch: true`.
   generated `run.sh` checked with `sh -n`. No new warnings in the changed lines.
 - **Not tested yet:** on the Frame (log line "Font: …", PNG written).
 
+### Fix: Quick Controls style Fusion (2026-10-08)
+
+- **Measurements on the Frame** (snapshots of the root page, OpenGL):
+  - Log: `Font: "Noto Sans" 9 pt = 12 px (requested "Sans Serif" 9 pt); 20 pt = 27 px;
+    screen "gamescope" logical DPI 96 physical DPI 63.972 device pixel ratio 1`. Fonts, DPI
+    and scaling are as intended.
+  - The PNG itself is cut off: OVRAS renders the content too large; SteamVR doesn't crop.
+  - Navigation buttons: as `qt6` is, 65 px (pitch 75) = Material. With
+    `QT_QUICK_CONTROLS_STYLE=Basic` (verified in the process environment): identical, the
+    import overrides it. Test build without the Material import (not committed): 45 px
+    (pitch 55) = Fusion, **everything fits**. Same build with Basic: 49 px (pitch 59), the
+    last button is cut off.
+- **Fix (DESIGN.md section 11):** `mainwidget.qml` imports `QtQuick.Controls` again;
+  `main.cpp` sets `QQuickStyle::setStyle("Fusion")`.
+- **Result:** cross build and package succeed, `Qt_6_PRIVATE_API` without `QVulkan*`: 0.
+- **Not tested yet:** the committed build on the Frame (expected as in the test build);
+  the other pages.
+- **Seen, not changed:** on "Chaperone" and "Space Fix" the icon still overlaps the text
+  slightly (`MyPushButton`: icon as wide as the button is high, text only indented by
+  spaces).
+
 ### Test checklist on the Frame (step 5)
 
 Deploy: `build_scripts/steamframe/deploy-to-frame.sh <user>@<frame>` (SteamVR running).
diff --git a/src/main.cpp b/src/main.cpp
index 9fefbbe..96953da 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -3,6 +3,7 @@
 #include "openvr/ovr_settings_wrapper.h"
 #include "render/RenderBackend.h"
 
+#include <QQuickStyle>
 #include <QtLogging>
 #include <QtDebug>
 #include <memory>
@@ -80,6 +81,15 @@ int main( int argc, char* argv[] )
     }
     QQuickWindow::setGraphicsApi( renderBackend->graphicsApi() );
 
+    // The QML layout has a fixed size (1200x800) and was made for Qt 5's
+    // default style. Without an explicit style, Qt 6 picks one per platform
+    // (Linux: Fusion, Windows: Windows), so the sizes would differ by
+    // platform. Fusion was measured on the Steam Frame: the root page fits
+    // (navigation buttons 45 px; Basic, Qt 5's style renamed: 49 px, the last
+    // button is cut off; Material: 65 px, a quarter is cut off). Must be set
+    // before any QML is loaded.
+    QQuickStyle::setStyle( "Fusion" );
+
     try
     {
         QQmlEngine qmlEngine;
diff --git a/src/res/qml/common/mainwidget.qml b/src/res/qml/common/mainwidget.qml
index 30dc057..8dc0c8e 100644
--- a/src/res/qml/common/mainwidget.qml
+++ b/src/res/qml/common/mainwidget.qml
@@ -1,5 +1,9 @@
 import QtQuick
-import QtQuick.Controls.Material
+// Not QtQuick.Controls.Material: importing a style module fixes that style
+// for all controls and overrides the one set in main.cpp. Material's
+// controls are too tall for the fixed-size layout (cut off on the Steam
+// Frame).
+import QtQuick.Controls
 import QtQuick.Layouts
 import ".."
 import "../utilities_page"