diff --git a/flying-saucer-core/src/main/java/org/xhtmlrenderer/context/StyleReference.java b/flying-saucer-core/src/main/java/org/xhtmlrenderer/context/StyleReference.java
index 722af8493..61b32987e 100644
--- a/flying-saucer-core/src/main/java/org/xhtmlrenderer/context/StyleReference.java
+++ b/flying-saucer-core/src/main/java/org/xhtmlrenderer/context/StyleReference.java
@@ -19,6 +19,8 @@
  */
 package org.xhtmlrenderer.context;
 
+import com.google.errorprone.annotations.CheckReturnValue;
+import org.jspecify.annotations.NonNull;
 import org.jspecify.annotations.Nullable;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
@@ -165,7 +167,9 @@ public CascadedStyle getCascadedStyle(@Nullable Element e, boolean restyle) {
         return _matcher.getCascadedStyle(e, restyle);
     }
 
-    public PageInfo getPageStyle(String pageName, String pseudoPage) {
+    @NonNull
+    @CheckReturnValue
+    public PageInfo getPageStyle(@Nullable String pageName, String pseudoPage) {
         return _matcher.getPageCascadedStyle(pageName, pseudoPage);
     }
 
diff --git a/flying-saucer-core/src/main/java/org/xhtmlrenderer/css/newmatch/Matcher.java b/flying-saucer-core/src/main/java/org/xhtmlrenderer/css/newmatch/Matcher.java
index dd4218cc8..53201de59 100644
--- a/flying-saucer-core/src/main/java/org/xhtmlrenderer/css/newmatch/Matcher.java
+++ b/flying-saucer-core/src/main/java/org/xhtmlrenderer/css/newmatch/Matcher.java
@@ -20,6 +20,8 @@
  */
 package org.xhtmlrenderer.css.newmatch;
 
+import com.google.errorprone.annotations.CheckReturnValue;
+import org.jspecify.annotations.NonNull;
 import org.jspecify.annotations.Nullable;
 import org.w3c.dom.Element;
 import org.w3c.dom.Node;
@@ -105,7 +107,9 @@ public CascadedStyle getPECascadedStyle(Element e, String pseudoElement) {
         }
     }
 
-    public PageInfo getPageCascadedStyle(String pageName, String pseudoPage) {
+    @NonNull
+    @CheckReturnValue
+    public PageInfo getPageCascadedStyle(@Nullable String pageName, String pseudoPage) {
         List<PropertyDeclaration> props = new ArrayList<>();
         Map<MarginBoxName, List<PropertyDeclaration>> marginBoxes = new HashMap<>();
 
diff --git a/flying-saucer-core/src/main/java/org/xhtmlrenderer/css/sheet/PageRule.java b/flying-saucer-core/src/main/java/org/xhtmlrenderer/css/sheet/PageRule.java
index 4e16b7ffb..1b37cf99c 100644
--- a/flying-saucer-core/src/main/java/org/xhtmlrenderer/css/sheet/PageRule.java
+++ b/flying-saucer-core/src/main/java/org/xhtmlrenderer/css/sheet/PageRule.java
@@ -19,6 +19,7 @@
  */
 package org.xhtmlrenderer.css.sheet;
 
+import org.jspecify.annotations.Nullable;
 import org.xhtmlrenderer.css.constants.MarginBoxName;
 import org.xhtmlrenderer.css.sheet.StylesheetInfo.Origin;
 
@@ -110,7 +111,7 @@ public long getOrder() {
         return result;
     }
 
-    public boolean applies(String pageName, String pseudoPage) {
+    public boolean applies(@Nullable String pageName, String pseudoPage) {
         if (_name == null && _pseudoPage == null) {
             return true;
         } else if (_name == null &&
diff --git a/flying-saucer-core/src/main/java/org/xhtmlrenderer/css/style/CalculatedStyle.java b/flying-saucer-core/src/main/java/org/xhtmlrenderer/css/style/CalculatedStyle.java
index ee0e5ea56..b6ff0634f 100644
--- a/flying-saucer-core/src/main/java/org/xhtmlrenderer/css/style/CalculatedStyle.java
+++ b/flying-saucer-core/src/main/java/org/xhtmlrenderer/css/style/CalculatedStyle.java
@@ -20,6 +20,8 @@
  */
 package org.xhtmlrenderer.css.style;
 
+import com.google.errorprone.annotations.CheckReturnValue;
+import org.jspecify.annotations.NonNull;
 import org.jspecify.annotations.Nullable;
 import org.xhtmlrenderer.css.constants.CSSName;
 import org.xhtmlrenderer.css.constants.IdentValue;
@@ -182,6 +184,8 @@ private static boolean checkBordersAllowed(IdentValue display) {
      * @param matched the CascadedStyle to apply
      * @return The derived child style
      */
+    @NonNull
+    @CheckReturnValue
     public CalculatedStyle deriveStyle(CascadedStyle matched) {
         String fingerprint = matched.getFingerprint();
         return _childCache.computeIfAbsent(fingerprint, (key) -> new CalculatedStyle(this, matched));
diff --git a/flying-saucer-core/src/main/java/org/xhtmlrenderer/layout/Layer.java b/flying-saucer-core/src/main/java/org/xhtmlrenderer/layout/Layer.java
index a69131aa5..7bd82cb0a 100644
--- a/flying-saucer-core/src/main/java/org/xhtmlrenderer/layout/Layer.java
+++ b/flying-saucer-core/src/main/java/org/xhtmlrenderer/layout/Layer.java
@@ -777,8 +777,6 @@ public void removeLastPage() {
 
     @CheckReturnValue
     public static PageBox createPageBox(CssContext c, String pseudoPage) {
-        PageBox result = new PageBox();
-
         String pageName = null;
         // HACK We only create pages during layout, but the OutputDevice
         // queries page positions and since pages are created lazily, changing
@@ -788,13 +786,8 @@ public static PageBox createPageBox(CssContext c, String pseudoPage) {
         }
 
         PageInfo pageInfo = c.getCss().getPageStyle(pageName, pseudoPage);
-        result.setPageInfo(pageInfo);
-
         CalculatedStyle cs = new EmptyStyle().deriveStyle(pageInfo.getPageStyle());
-        result.setStyle(cs);
-        result.setOuterPageWidth(result.getWidth(c));
-
-        return result;
+        return new PageBox(pageInfo, c, cs);
     }
 
     @Nullable
diff --git a/flying-saucer-core/src/main/java/org/xhtmlrenderer/render/PageBox.java b/flying-saucer-core/src/main/java/org/xhtmlrenderer/render/PageBox.java
index c326fff3f..78537316e 100644
--- a/flying-saucer-core/src/main/java/org/xhtmlrenderer/render/PageBox.java
+++ b/flying-saucer-core/src/main/java/org/xhtmlrenderer/render/PageBox.java
@@ -20,6 +20,7 @@
 package org.xhtmlrenderer.render;
 
 import com.google.errorprone.annotations.CheckReturnValue;
+import org.jspecify.annotations.NonNull;
 import org.jspecify.annotations.Nullable;
 import org.w3c.dom.Element;
 import org.w3c.dom.css.CSSPrimitiveValue;
@@ -74,8 +75,7 @@ public class PageBox {
 
     private static final int LEADING_TRAILING_SPLIT = 5;
 
-    @Nullable
-    private CalculatedStyle _style;
+    private final CalculatedStyle _style;
 
     private int _top;
     private int _bottom;
@@ -85,13 +85,13 @@ public class PageBox {
 
     private int _pageNo;
 
-    private int _outerPageWidth;
+    private final int _outerPageWidth;
 
     @Nullable
     private PageDimensions _pageDimensions;
 
-    @Nullable
-    private PageInfo _pageInfo;
+    @NonNull
+    private final PageInfo _pageInfo;
 
     @Nullable
     private final MarginAreaContainer[] _marginAreas = new MarginAreaContainer[MARGIN_AREA_DEFS.length];
@@ -99,6 +99,12 @@ public class PageBox {
     @Nullable
     private Element _metadata;
 
+    public PageBox(PageInfo pageInfo, CssContext cssContext, CalculatedStyle style) {
+        _pageInfo = pageInfo;
+        _style = style;
+        _outerPageWidth = getWidth(cssContext);
+    }
+
     public int getWidth(CssContext cssCtx) {
         return getPageDimensions(cssCtx).width();
     }
@@ -211,10 +217,6 @@ public CalculatedStyle getStyle() {
         return _style;
     }
 
-    public void setStyle(CalculatedStyle style) {
-        _style = style;
-    }
-
     public int getBottom() {
         return _bottom;
     }
@@ -333,10 +335,6 @@ public int getOuterPageWidth() {
         return _outerPageWidth;
     }
 
-    public void setOuterPageWidth(int containingBlockWidth) {
-        _outerPageWidth = containingBlockWidth;
-    }
-
     public int getMarginBorderPadding(CssContext cssCtx, Edge edge) {
         return getStyle().getMarginBorderPadding(cssCtx, getOuterPageWidth(), edge);
     }
@@ -345,10 +343,6 @@ public PageInfo getPageInfo() {
         return _pageInfo;
     }
 
-    public void setPageInfo(PageInfo pageInfo) {
-        _pageInfo = pageInfo;
-    }
-
     @Nullable
     @CheckReturnValue
     public Element getMetadata() {
@@ -451,7 +445,7 @@ private record PageDimensions(int width, int height) {
     private record MarginAreaContainer(MarginArea area, TableBox table) {
     }
 
-    private abstract static class MarginArea {
+    private abstract static sealed class MarginArea {
         private final MarginBoxName[] _marginBoxNames;
 
         public abstract Dimension getLayoutDimension(CssContext c, PageBox page, RectPropertySet margin);
@@ -477,7 +471,7 @@ public MarginDirection getDirection() {
         }
     }
 
-    private static class TopLeftCorner extends MarginArea {
+    private static final class TopLeftCorner extends MarginArea {
         private TopLeftCorner() {
             super(MarginBoxName.TOP_LEFT_CORNER);
         }
@@ -498,7 +492,7 @@ public Point getPaintingPosition(RenderingContext c, PageBox page, int additiona
 
     }
 
-    private static class TopRightCorner extends MarginArea {
+    private static final class TopRightCorner extends MarginArea {
         private TopRightCorner() {
             super(MarginBoxName.TOP_RIGHT_CORNER);
         }
@@ -519,7 +513,7 @@ public Point getPaintingPosition(RenderingContext c, PageBox page, int additiona
         }
     }
 
-    private static class BottomRightCorner extends MarginArea {
+    private static final class BottomRightCorner extends MarginArea {
         private BottomRightCorner() {
             super(MarginBoxName.BOTTOM_RIGHT_CORNER);
         }
@@ -540,7 +534,7 @@ public Point getPaintingPosition(RenderingContext c, PageBox page, int additiona
         }
     }
 
-    private static class BottomLeftCorner extends MarginArea {
+    private static final class BottomLeftCorner extends MarginArea {
         private BottomLeftCorner() {
             super(MarginBoxName.BOTTOM_LEFT_CORNER);
         }
@@ -560,7 +554,7 @@ public Point getPaintingPosition(RenderingContext c, PageBox page, int additiona
         }
     }
 
-    private static class LeftMarginArea extends MarginArea {
+    private static final class LeftMarginArea extends MarginArea {
         private LeftMarginArea() {
             super(new MarginBoxName[] {
                     MarginBoxName.LEFT_TOP,
@@ -587,7 +581,7 @@ public MarginDirection getDirection() {
         }
     }
 
-    private static class RightMarginArea extends MarginArea {
+    private static final class RightMarginArea extends MarginArea {
         private RightMarginArea() {
             super(new MarginBoxName[] {
                     MarginBoxName.RIGHT_TOP,
@@ -615,7 +609,7 @@ public MarginDirection getDirection() {
         }
     }
 
-    private static class TopMarginArea extends MarginArea {
+    private static final class TopMarginArea extends MarginArea {
         private TopMarginArea() {
             super(new MarginBoxName[] {
                     MarginBoxName.TOP_LEFT,
@@ -639,7 +633,7 @@ public Point getPaintingPosition(RenderingContext c, PageBox page, int additiona
         }
     }
 
-    private static class BottomMarginArea extends MarginArea {
+    private static final class BottomMarginArea extends MarginArea {
         private BottomMarginArea() {
             super(new MarginBoxName[] {
                     MarginBoxName.BOTTOM_LEFT,