diff --git a/lib/GfxRenderer/GfxRenderer.cpp b/lib/GfxRenderer/GfxRenderer.cpp
index 474511b..f078972 100644
--- a/lib/GfxRenderer/GfxRenderer.cpp
+++ b/lib/GfxRenderer/GfxRenderer.cpp
@@ -250,6 +250,55 @@ void GfxRenderer::fillRect(const int x, const int y, const int width, const int
   }
 }
 
+// Use Bayer matrix 4x4 dithering to fill the rectangle with a grey level - 0 white to 15 black
+void GfxRenderer::fillRectGrey(const int x, const int y, const int width, const int height, const int greyLevel) const {
+  static constexpr uint8_t bayer4x4[4][4] = {
+      {0, 8, 2, 10},
+      {12, 4, 14, 6},
+      {3, 11, 1, 9},
+      {15, 7, 13, 5},
+  };
+  static constexpr int matrixSize = 4;
+  static constexpr int matrixLevels = matrixSize * matrixSize;
+
+  const int normalizedGrey = (greyLevel * 255) / (matrixLevels - 1);
+  const int clampedGrey = std::max(0, std::min(normalizedGrey, 255));
+  const int threshold = (clampedGrey * (matrixLevels + 1)) / 256;
+
+  for (int dy = 0; dy < height; ++dy) {
+    const int screenY = y + dy;
+    const int matrixY = screenY & (matrixSize - 1);
+    for (int dx = 0; dx < width; ++dx) {
+      const int screenX = x + dx;
+      const int matrixX = screenX & (matrixSize - 1);
+      const uint8_t patternValue = bayer4x4[matrixY][matrixX];
+      const bool black = patternValue < threshold;
+      drawPixel(screenX, screenY, black);
+    }
+  }
+}
+
+// Color -1 white, 0 clear, 1 black
+void GfxRenderer::fillArc(const int maxRadius, const int cx, const int cy, const int xDir, const int yDir, const int insideColor, const int outsideColor) const {
+  const int radiusSq = maxRadius * maxRadius;
+  for (int dy = 0; dy <= maxRadius; ++dy) {
+    for (int dx = 0; dx <= maxRadius; ++dx) {
+      const int distSq = dx * dx + dy * dy;
+      const int px = cx + xDir * dx;
+      const int py = cy + yDir * dy;
+      if (distSq > radiusSq) {
+        if (outsideColor != 0) {
+          drawPixel(px, py, outsideColor == 1);
+        }
+      } else {
+        if (insideColor != 0) {
+          drawPixel(px, py, insideColor == 1);
+        }
+      }
+    }
+  }
+};
+
 void GfxRenderer::drawImage(const uint8_t bitmap[], const int x, const int y, const int width, const int height) const {
   // Flip X and Y for portrait mode
   einkDisplay.drawImage(bitmap, y, x, height, width);
diff --git a/lib/GfxRenderer/GfxRenderer.h b/lib/GfxRenderer/GfxRenderer.h
index 7c36533..32ba525 100644
--- a/lib/GfxRenderer/GfxRenderer.h
+++ b/lib/GfxRenderer/GfxRenderer.h
@@ -51,6 +51,8 @@ class GfxRenderer {
   void drawArc(int maxRadius, int cx, int cy, int xDir, int yDir, int lineWidth, bool state) const;
   void drawRoundedRect(int x, int y, int width, int height, int lineWidth, int cornerRadius, bool state) const;
   void fillRect(int x, int y, int width, int height, bool state = true) const;
+  void fillRectGrey(int x, int y, int width, int height, int greyLevel) const;
+  void fillArc(int maxRadius, int cx, int cy, int xDir, int yDir, int insideColor, int outsideColor) const;
   void drawImage(const uint8_t bitmap[], int x, int y, int width, int height) const;
   void drawIcon(const uint8_t bitmap[], int x, int y, int width, int height) const;
   void drawBitmap(const Bitmap& bitmap, int x, int y, int maxWidth, int maxHeight) const;
diff --git a/src/activities/home/GridBrowserActivity.cpp b/src/activities/home/GridBrowserActivity.cpp
index cd642f5..8823dc5 100644
--- a/src/activities/home/GridBrowserActivity.cpp
+++ b/src/activities/home/GridBrowserActivity.cpp
@@ -17,7 +17,7 @@ constexpr int TILE_PADDING = 5;
 constexpr int THUMB_W = 90;
 constexpr int THUMB_H = 120;
 constexpr int TILE_TEXT_H = 60;
-constexpr int gridLeftOffset = 45;
+constexpr int gridLeftOffset = 37;
 constexpr int gridTopOffset = 125;
 }  // namespace
 
@@ -61,7 +61,7 @@ void GridBrowserActivity::loadFiles() {
         std::string ext = filename.substr(dot);
         basename = filename.substr(0, dot); 
         // lowercase ext for case-insensitive compare
-        for (char &c : ext) c = (char)tolower(c);
+        std::transform(ext.begin(), ext.end(), ext.begin(), [](unsigned char c){ return std::tolower(c); });
         if (ext == ".epub") {
           type = F_EPUB;
         } else if (ext == ".thumb.bmp") {
@@ -136,7 +136,7 @@ void GridBrowserActivity::loop() {
     }
   } else if (inputManager.wasPressed(InputManager::BTN_BACK)) {
     if (basepath != "/") {
-      basepath = basepath.substr(0, basepath.rfind('/'));
+      basepath.resize(basepath.rfind('/'));
       if (basepath.empty()) basepath = "/";
       loadFiles();
       renderRequired = true;
@@ -197,9 +197,9 @@ void GridBrowserActivity::render(bool clear) const {
     auto folderName = basepath == "/" ? "SD card" : basepath.substr(basepath.rfind('/') + 1).c_str();
     drawFullscreenWindowFrame(renderer, folderName);
   }
-  bool hasGeyscaleBitmaps = false;
   
   if (!files.empty()) {
+    bool hasGeyscaleBitmaps = false;
     for (int pass = 0; pass < 3; pass++) {
       if (pass > 0) {
         renderer.clearScreen(0x00);
@@ -255,7 +255,7 @@ void GridBrowserActivity::render(bool clear) const {
         }
       } else if (pass == 1) {
         renderer.copyGrayscaleLsbBuffers();
-      } else if (pass == 2) {
+      } else {
         renderer.copyGrayscaleMsbBuffers();
         renderer.displayGrayBuffer();
         renderer.setRenderMode(GfxRenderer::BW);
diff --git a/src/activities/home/GridBrowserActivity.h b/src/activities/home/GridBrowserActivity.h
index c3a0cd9..f950cf4 100644
--- a/src/activities/home/GridBrowserActivity.h
+++ b/src/activities/home/GridBrowserActivity.h
@@ -30,7 +30,7 @@ class GridBrowserActivity final : public Activity {
   std::vector<FileInfo> files;
   int selectorIndex = 0;
   int previousSelectorIndex = -1;
-  int page;
+  int page = 0;
   bool updateRequired = false;
   bool renderRequired = false;
   const std::function<void(const std::string&)> onSelect;
diff --git a/src/activities/util/Window.cpp b/src/activities/util/Window.cpp
index d3774d6..c701d4d 100644
--- a/src/activities/util/Window.cpp
+++ b/src/activities/util/Window.cpp
@@ -14,6 +14,13 @@ constexpr int batteryHeight = 10;
 
 void drawWindowFrame(GfxRenderer& renderer, int xMargin, int y, int height, bool hasShadow, const char* title) {
     const int windowWidth = GfxRenderer::getScreenWidth() - 2 * xMargin;
+
+    if (title) { // Header background
+        renderer.fillRectGrey(xMargin, y, windowWidth, windowHeaderHeight, 5);
+        renderer.fillArc(windowCornerRadius, xMargin + windowCornerRadius, y + windowCornerRadius, -1, -1, 0, -1);               // TL
+        renderer.fillArc(windowCornerRadius, windowWidth + xMargin - windowCornerRadius, y + windowCornerRadius, 1, -1, 0, -1);  // TR
+    }
+    
     renderer.drawRoundedRect(xMargin, y, windowWidth, height, windowBorderWidth, windowCornerRadius, true);
 
     if (hasShadow) {
@@ -43,7 +50,6 @@ void drawStatusBar(GfxRenderer& renderer) {
     // Left aligned battery icon and percentage
     const uint16_t percentage = battery.readPercentage();
     const auto percentageText = std::to_string(percentage) + "%";
-    const auto percentageTextWidth = renderer.getTextWidth(SMALL_FONT_ID, percentageText.c_str());
     renderer.drawText(SMALL_FONT_ID, fullscreenWindowMargin + batteryWidth + 5, textY, percentageText.c_str());
 
     // 1 column on left, 2 columns on right, 5 columns of battery body