diff --git a/packages/plugins/pdf/test/helpers/fake_slide_capture_service.dart b/packages/plugins/pdf/test/helpers/fake_slide_capture_service.dart
index 20197f9b..857b75e4 100644
--- a/packages/plugins/pdf/test/helpers/fake_slide_capture_service.dart
+++ b/packages/plugins/pdf/test/helpers/fake_slide_capture_service.dart
@@ -18,6 +18,7 @@ class FakeSlideCaptureService extends SlideCaptureService {
     SlideCaptureQuality quality = SlideCaptureQuality.thumbnail,
     required SlideConfiguration slide,
     required BuildContext context,
+    bool includeDebugLayout = false,
   }) async {
     return bytes;
   }
diff --git a/packages/superdeck/lib/src/capture/slide_capture_service.dart b/packages/superdeck/lib/src/capture/slide_capture_service.dart
index a9852309..5656c76c 100644
--- a/packages/superdeck/lib/src/capture/slide_capture_service.dart
+++ b/packages/superdeck/lib/src/capture/slide_capture_service.dart
@@ -45,8 +45,11 @@ class SlideCaptureService {
     SlideCaptureQuality quality = SlideCaptureQuality.thumbnail,
     required SlideConfiguration slide,
     required BuildContext context,
+    bool includeDebugLayout = false,
   }) async {
-    final queueKey = shortHash(slide.key + quality.name);
+    final queueKey = shortHash(
+      '${slide.key}${quality.name}$includeDebugLayout',
+    );
     try {
       while (_generationQueue.length >= _maxConcurrentGenerations) {
         await Future.delayed(_kQueuePollInterval);
@@ -55,7 +58,7 @@ class SlideCaptureService {
       _generationQueue.add(queueKey);
 
       final staticRenderingSlide = slide.copyWith(
-        debug: false,
+        debug: includeDebugLayout,
         isStaticRendering: true,
       );
 
diff --git a/packages/superdeck/lib/src/rendering/blocks/block_widget.dart b/packages/superdeck/lib/src/rendering/blocks/block_widget.dart
index 4a982ff5..bc8bdff9 100644
--- a/packages/superdeck/lib/src/rendering/blocks/block_widget.dart
+++ b/packages/superdeck/lib/src/rendering/blocks/block_widget.dart
@@ -1,6 +1,5 @@
 import 'dart:math' as math;
 
-import 'package:flutter/material.dart' show Colors;
 import 'package:flutter/widgets.dart';
 import 'package:mix/mix.dart';
 import 'package:superdeck_core/superdeck_core.dart';
@@ -12,6 +11,7 @@ import '../../ui/widgets/error_widgets.dart';
 import '../../ui/widgets/overflow_clip.dart';
 import '../../ui/widgets/provider.dart';
 import '../../utils/converters.dart';
+import '../layout_debug_overlay.dart';
 import 'block_provider.dart';
 import 'markdown_viewer.dart';
 
@@ -141,13 +141,11 @@ class _BlockContainerState extends State<_BlockContainer> {
       ),
     );
 
-    // Add debug border if needed
-    if (widget.configuration.debug) {
-      content = DecoratedBox(
-        position: DecorationPosition.foreground,
-        decoration: BoxDecoration(
-          border: Border.all(color: Colors.cyan, width: 2),
-        ),
+    final debugLayoutEnabled = widget.configuration.debug;
+    if (debugLayoutEnabled) {
+      content = BlockLayoutDebugOverlay(
+        margin: spec.blockContainer.spec.margin,
+        padding: spec.blockContainer.spec.padding,
         child: content,
       );
     }
@@ -336,20 +334,15 @@ class SectionWidget extends StatelessWidget {
   final SectionBlock section;
   final int sectionIndex;
 
-  Positioned _renderDebugInfo(Block block, Size size) {
-    const textStyle = TextStyle(color: Colors.black, fontSize: 12);
-    final label =
-        '''
-@${block.type}
-${size.width.toStringAsFixed(2)} x ${size.height.toStringAsFixed(2)}''';
-
+  Positioned _renderDebugInfo(Block block, int blockIndex, Size size) {
     return Positioned(
       top: 0,
       right: 0,
-      child: Container(
-        color: Colors.cyan,
-        padding: const EdgeInsets.all(8),
-        child: Text(label, style: textStyle),
+      child: LayoutDebugLabel(
+        color: debugBlockColor,
+        text:
+            'BLOCK ${blockIndex + 1}  @${block.type}\n'
+            '${size.width.toStringAsFixed(0)} × ${size.height.toStringAsFixed(0)}',
       ),
     );
   }
@@ -401,13 +394,18 @@ ${size.width.toStringAsFixed(2)} x ${size.height.toStringAsFixed(2)}''';
                       ),
                     };
 
-                    if (!configuration.debug) return blockWidget;
+                    final debugLayoutEnabled = configuration.debug;
+                    if (!debugLayoutEnabled) return blockWidget;
                     return LayoutBuilder(
                       builder: (context, constraints) => Stack(
                         fit: StackFit.expand,
                         children: [
                           blockWidget,
-                          _renderDebugInfo(block, constraints.biggest),
+                          _renderDebugInfo(
+                            block,
+                            blockIndex,
+                            constraints.biggest,
+                          ),
                         ],
                       ),
                     );
diff --git a/packages/superdeck/lib/src/rendering/layout_debug_overlay.dart b/packages/superdeck/lib/src/rendering/layout_debug_overlay.dart
new file mode 100644
index 00000000..e4469865
--- /dev/null
+++ b/packages/superdeck/lib/src/rendering/layout_debug_overlay.dart
@@ -0,0 +1,193 @@
+import 'dart:math' as math;
+
+import 'package:flutter/widgets.dart';
+
+const debugSectionColor = Color(0xFFFF4DCD);
+const debugBlockColor = Color(0xFF00D5FF);
+const debugMarginColor = Color(0xFFFFA62B);
+const debugPaddingColor = Color(0xFF35E06F);
+
+/// Draws a debug-only frame without participating in layout.
+class LayoutDebugFrame extends StatelessWidget {
+  final Color color;
+  final Widget child;
+  final double strokeWidth;
+
+  const LayoutDebugFrame({
+    super.key,
+    required this.color,
+    required this.child,
+    this.strokeWidth = 3,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return CustomPaint(
+      foregroundPainter: _FramePainter(color, strokeWidth),
+      child: child,
+    );
+  }
+}
+
+/// Draws the allocated block, resolved margin, and resolved padding edges.
+class BlockLayoutDebugOverlay extends StatelessWidget {
+  final EdgeInsetsGeometry? margin;
+  final EdgeInsetsGeometry? padding;
+  final Widget child;
+
+  const BlockLayoutDebugOverlay({
+    super.key,
+    required this.margin,
+    required this.padding,
+    required this.child,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    final textDirection = Directionality.maybeOf(context) ?? TextDirection.ltr;
+    return CustomPaint(
+      foregroundPainter: _BlockInsetsPainter(
+        margin: margin?.resolve(textDirection) ?? EdgeInsets.zero,
+        padding: padding?.resolve(textDirection) ?? EdgeInsets.zero,
+      ),
+      child: child,
+    );
+  }
+}
+
+class LayoutDebugLabel extends StatelessWidget {
+  final Color color;
+  final String text;
+
+  const LayoutDebugLabel({super.key, required this.color, required this.text});
+
+  @override
+  Widget build(BuildContext context) {
+    return ColoredBox(
+      color: color,
+      child: Padding(
+        padding: const EdgeInsets.symmetric(horizontal: 6, vertical: 3),
+        child: Text(
+          text,
+          style: const TextStyle(
+            color: Color(0xFF071018),
+            fontSize: 11,
+            fontWeight: FontWeight.w700,
+            height: 1.2,
+          ),
+        ),
+      ),
+    );
+  }
+}
+
+class LayoutDebugLegend extends StatelessWidget {
+  const LayoutDebugLegend({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return ColoredBox(
+      color: const Color(0xE6071018),
+      child: Padding(
+        padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 6),
+        child: Row(
+          mainAxisSize: MainAxisSize.min,
+          children: const [
+            _LegendItem(color: debugSectionColor, label: 'SECTION'),
+            SizedBox(width: 10),
+            _LegendItem(color: debugBlockColor, label: 'BLOCK'),
+            SizedBox(width: 10),
+            _LegendItem(color: debugMarginColor, label: 'MARGIN'),
+            SizedBox(width: 10),
+            _LegendItem(color: debugPaddingColor, label: 'PADDING'),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+class _LegendItem extends StatelessWidget {
+  final Color color;
+  final String label;
+
+  const _LegendItem({required this.color, required this.label});
+
+  @override
+  Widget build(BuildContext context) {
+    return Row(
+      mainAxisSize: MainAxisSize.min,
+      children: [
+        SizedBox.square(dimension: 10, child: ColoredBox(color: color)),
+        const SizedBox(width: 4),
+        Text(
+          label,
+          style: const TextStyle(
+            color: Color(0xFFFFFFFF),
+            fontSize: 10,
+            fontWeight: FontWeight.w700,
+          ),
+        ),
+      ],
+    );
+  }
+}
+
+class _BlockInsetsPainter extends CustomPainter {
+  final EdgeInsets margin;
+  final EdgeInsets padding;
+
+  const _BlockInsetsPainter({required this.margin, required this.padding});
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    final blockRect = Offset.zero & size;
+    final marginRect = _inset(blockRect, margin);
+    final paddingRect = _inset(marginRect, padding);
+
+    _drawFrame(canvas, blockRect, debugBlockColor, 4);
+    _drawFrame(canvas, marginRect, debugMarginColor, 3);
+    _drawFrame(canvas, paddingRect, debugPaddingColor, 2);
+  }
+
+  @override
+  bool shouldRepaint(_BlockInsetsPainter oldDelegate) {
+    return oldDelegate.margin != margin || oldDelegate.padding != padding;
+  }
+}
+
+class _FramePainter extends CustomPainter {
+  final Color color;
+  final double strokeWidth;
+
+  const _FramePainter(this.color, this.strokeWidth);
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    _drawFrame(canvas, Offset.zero & size, color, strokeWidth);
+  }
+
+  @override
+  bool shouldRepaint(_FramePainter oldDelegate) {
+    return oldDelegate.color != color || oldDelegate.strokeWidth != strokeWidth;
+  }
+}
+
+Rect _inset(Rect rect, EdgeInsets insets) {
+  final left = math.min(rect.right, rect.left + insets.left);
+  final top = math.min(rect.bottom, rect.top + insets.top);
+  final right = math.max(left, rect.right - insets.right);
+  final bottom = math.max(top, rect.bottom - insets.bottom);
+  return Rect.fromLTRB(left, top, right, bottom);
+}
+
+void _drawFrame(Canvas canvas, Rect rect, Color color, double strokeWidth) {
+  if (rect.width <= strokeWidth || rect.height <= strokeWidth) return;
+  canvas.drawRect(
+    rect.deflate(strokeWidth / 2),
+    Paint()
+      ..color = color
+      ..style = PaintingStyle.stroke
+      ..strokeWidth = strokeWidth,
+  );
+}
diff --git a/packages/superdeck/lib/src/rendering/slides/slide_view.dart b/packages/superdeck/lib/src/rendering/slides/slide_view.dart
index 6df779c4..2325d614 100644
--- a/packages/superdeck/lib/src/rendering/slides/slide_view.dart
+++ b/packages/superdeck/lib/src/rendering/slides/slide_view.dart
@@ -1,4 +1,3 @@
-import 'package:flutter/material.dart' show Colors;
 import 'package:flutter/widgets.dart';
 import 'package:mix/mix.dart';
 import 'package:superdeck_core/superdeck_core.dart';
@@ -7,6 +6,7 @@ import '../../deck/slide_configuration.dart';
 import '../../styling/components/slide.dart';
 import '../../utils/constants.dart';
 import '../blocks/block_widget.dart';
+import '../layout_debug_overlay.dart';
 
 class SlideView extends StatelessWidget {
   final SlideConfiguration slide;
@@ -18,18 +18,20 @@ class SlideView extends StatelessWidget {
         : const SizedBox.shrink();
   }
 
-  Positioned _renderDebugInfo(SectionBlock section, Size slideSize) {
-    final label = '''
-@section | blocks: ${section.blocks.length} | ${slideSize.width.toStringAsFixed(2)} x ${slideSize.height.toStringAsFixed(2)} | align: ${section.align} | flex: ${section.flex}''';
-
-    const textStyle = TextStyle(color: Colors.black, fontSize: 12);
+  Positioned _renderDebugInfo(
+    SectionBlock section,
+    int sectionIndex,
+    Size slideSize,
+  ) {
     return Positioned(
       bottom: 0,
-      left: 0,
-      child: Container(
-        color: Colors.cyan,
-        padding: const EdgeInsets.all(8),
-        child: Text(label, style: textStyle),
+      right: 0,
+      child: LayoutDebugLabel(
+        color: debugSectionColor,
+        text:
+            'SECTION ${sectionIndex + 1}  blocks:${section.blocks.length}  '
+            '${slideSize.width.toStringAsFixed(0)} × '
+            '${slideSize.height.toStringAsFixed(0)}',
       ),
     );
   }
@@ -57,9 +59,22 @@ class SlideView extends StatelessWidget {
                 return Stack(
                   fit: StackFit.expand,
                   children: [
-                    SectionWidget(section: section, sectionIndex: sectionIndex),
                     if (configuration.debug)
-                      _renderDebugInfo(section, sectionSize),
+                      LayoutDebugFrame(
+                        color: debugSectionColor,
+                        strokeWidth: 4,
+                        child: SectionWidget(
+                          section: section,
+                          sectionIndex: sectionIndex,
+                        ),
+                      )
+                    else
+                      SectionWidget(
+                        section: section,
+                        sectionIndex: sectionIndex,
+                      ),
+                    if (configuration.debug)
+                      _renderDebugInfo(section, sectionIndex, sectionSize),
                   ],
                 );
               },
@@ -133,6 +148,12 @@ class SlideView extends StatelessWidget {
               },
             ),
           ),
+          if (slide.debug)
+            const Positioned(
+              left: 8,
+              bottom: 8,
+              child: IgnorePointer(child: LayoutDebugLegend()),
+            ),
         ],
       ),
     );
diff --git a/packages/superdeck/lib/src/styling/components/block_styler.dart b/packages/superdeck/lib/src/styling/components/block_styler.dart
index c5e69db5..4e586918 100644
--- a/packages/superdeck/lib/src/styling/components/block_styler.dart
+++ b/packages/superdeck/lib/src/styling/components/block_styler.dart
@@ -18,8 +18,8 @@ import 'package:mix/mix.dart';
 /// It intentionally cannot express widget modifiers, width/height or other
 /// constraints, transforms, box alignment, or widget-state variants — those
 /// would create competing geometry owners with section `spacing`, block
-/// `flex`, and block/section `align`. Extending this allow-list is a design
-/// decision, not a convenience patch; see `.planning` notes for PR #99.
+/// `flex`, and block/section `align`. Extending this allow-list is a framework
+/// design decision because it changes which layer owns block geometry.
 final class BlockStyler extends Style<BoxSpec>
     with
         Diagnosticable,
diff --git a/packages/superdeck/lib/src/styling/components/slide.dart b/packages/superdeck/lib/src/styling/components/slide.dart
index e12ccccb..f49acaa6 100644
--- a/packages/superdeck/lib/src/styling/components/slide.dart
+++ b/packages/superdeck/lib/src/styling/components/slide.dart
@@ -62,6 +62,13 @@ final class SlideSpec with _$SlideSpec {
   @override
   final TextScaler? textScaleFactor;
 
+  /// Vertical gap between top-level markdown elements.
+  ///
+  /// An unset value resolves to zero so spacing is owned by SuperDeck styles,
+  /// not by flutter_markdown_plus package defaults.
+  @override
+  final double? blockSpacing;
+
   @override
   final StyleSpec<MarkdownAlertSpec> alert;
   @override
@@ -106,6 +113,7 @@ final class SlideSpec with _$SlideSpec {
     this.img,
     this.link,
     this.textScaleFactor,
+    this.blockSpacing,
     StyleSpec<MarkdownAlertSpec>? alert,
     this.horizontalRuleDecoration,
     this.blockquote,
@@ -141,6 +149,7 @@ final class SlideSpec with _$SlideSpec {
       del: del,
       code: code?.spec.textStyle,
       textScaler: textScaleFactor,
+      blockSpacing: blockSpacing ?? 0,
       listBullet: list?.spec.bullet?.spec.style,
       orderedListAlign: list?.spec.orderedAlignment ?? WrapAlignment.start,
       unorderedListAlign: list?.spec.unorderedAlignment ?? WrapAlignment.start,
diff --git a/packages/superdeck/lib/src/styling/components/slide.g.dart b/packages/superdeck/lib/src/styling/components/slide.g.dart
index cc724f41..17453704 100644
--- a/packages/superdeck/lib/src/styling/components/slide.g.dart
+++ b/packages/superdeck/lib/src/styling/components/slide.g.dart
@@ -21,6 +21,7 @@ mixin _$SlideSpec implements Spec<SlideSpec>, Diagnosticable {
   TextStyle? get img;
   TextStyle? get link;
   TextScaler? get textScaleFactor;
+  double? get blockSpacing;
   StyleSpec<MarkdownAlertSpec> get alert;
   BoxDecoration? get horizontalRuleDecoration;
   StyleSpec<MarkdownBlockquoteSpec>? get blockquote;
@@ -51,6 +52,7 @@ mixin _$SlideSpec implements Spec<SlideSpec>, Diagnosticable {
     TextStyle? img,
     TextStyle? link,
     TextScaler? textScaleFactor,
+    double? blockSpacing,
     StyleSpec<MarkdownAlertSpec>? alert,
     BoxDecoration? horizontalRuleDecoration,
     StyleSpec<MarkdownBlockquoteSpec>? blockquote,
@@ -77,6 +79,7 @@ mixin _$SlideSpec implements Spec<SlideSpec>, Diagnosticable {
       img: img ?? this.img,
       link: link ?? this.link,
       textScaleFactor: textScaleFactor ?? this.textScaleFactor,
+      blockSpacing: blockSpacing ?? this.blockSpacing,
       alert: alert ?? this.alert,
       horizontalRuleDecoration:
           horizontalRuleDecoration ?? this.horizontalRuleDecoration,
@@ -112,6 +115,7 @@ mixin _$SlideSpec implements Spec<SlideSpec>, Diagnosticable {
         other?.textScaleFactor,
         t,
       ),
+      blockSpacing: MixOps.lerp(blockSpacing, other?.blockSpacing, t),
       alert: alert.lerp(other?.alert, t),
       horizontalRuleDecoration: MixOps.lerp(
         horizontalRuleDecoration,
@@ -145,6 +149,7 @@ mixin _$SlideSpec implements Spec<SlideSpec>, Diagnosticable {
     img,
     link,
     textScaleFactor,
+    blockSpacing,
     alert,
     horizontalRuleDecoration,
     blockquote,
@@ -211,6 +216,7 @@ mixin _$SlideSpec implements Spec<SlideSpec>, Diagnosticable {
       ..add(DiagnosticsProperty('img', img))
       ..add(DiagnosticsProperty('link', link))
       ..add(DiagnosticsProperty('textScaleFactor', textScaleFactor))
+      ..add(DoubleProperty('blockSpacing', blockSpacing))
       ..add(DiagnosticsProperty('alert', alert))
       ..add(
         DiagnosticsProperty(
@@ -253,6 +259,7 @@ class SlideStyler extends MixStyler<SlideStyler, SlideSpec> {
   final Prop<TextStyle>? $img;
   final Prop<TextStyle>? $link;
   final Prop<TextScaler>? $textScaleFactor;
+  final Prop<double>? $blockSpacing;
   final Prop<StyleSpec<MarkdownAlertSpec>>? $alert;
   final Prop<BoxDecoration>? $horizontalRuleDecoration;
   final Prop<StyleSpec<MarkdownBlockquoteSpec>>? $blockquote;
@@ -279,6 +286,7 @@ class SlideStyler extends MixStyler<SlideStyler, SlideSpec> {
     Prop<TextStyle>? img,
     Prop<TextStyle>? link,
     Prop<TextScaler>? textScaleFactor,
+    Prop<double>? blockSpacing,
     Prop<StyleSpec<MarkdownAlertSpec>>? alert,
     Prop<BoxDecoration>? horizontalRuleDecoration,
     Prop<StyleSpec<MarkdownBlockquoteSpec>>? blockquote,
@@ -306,6 +314,7 @@ class SlideStyler extends MixStyler<SlideStyler, SlideSpec> {
        $img = img,
        $link = link,
        $textScaleFactor = textScaleFactor,
+       $blockSpacing = blockSpacing,
        $alert = alert,
        $horizontalRuleDecoration = horizontalRuleDecoration,
        $blockquote = blockquote,
@@ -332,6 +341,7 @@ class SlideStyler extends MixStyler<SlideStyler, SlideSpec> {
     TextStyleMix? img,
     TextStyleMix? link,
     TextScaler? textScaleFactor,
+    double? blockSpacing,
     MarkdownAlertStyler? alert,
     BoxDecoration? horizontalRuleDecoration,
     MarkdownBlockquoteStyler? blockquote,
@@ -360,6 +370,7 @@ class SlideStyler extends MixStyler<SlideStyler, SlideSpec> {
          img: Prop.maybeMix(img),
          link: Prop.maybeMix(link),
          textScaleFactor: Prop.maybe(textScaleFactor),
+         blockSpacing: Prop.maybe(blockSpacing),
          alert: Prop.maybeMix(alert),
          horizontalRuleDecoration: Prop.maybe(horizontalRuleDecoration),
          blockquote: Prop.maybeMix(blockquote),
@@ -390,6 +401,8 @@ class SlideStyler extends MixStyler<SlideStyler, SlideSpec> {
   factory SlideStyler.link(TextStyleMix value) => SlideStyler().link(value);
   factory SlideStyler.textScaleFactor(TextScaler value) =>
       SlideStyler().textScaleFactor(value);
+  factory SlideStyler.blockSpacing(double value) =>
+      SlideStyler().blockSpacing(value);
   factory SlideStyler.alert(MarkdownAlertStyler value) =>
       SlideStyler().alert(value);
   factory SlideStyler.horizontalRuleDecoration(BoxDecoration value) =>
@@ -480,6 +493,11 @@ class SlideStyler extends MixStyler<SlideStyler, SlideSpec> {
     return merge(SlideStyler(textScaleFactor: value));
   }
 
+  /// Sets the blockSpacing.
+  SlideStyler blockSpacing(double value) {
+    return merge(SlideStyler(blockSpacing: value));
+  }
+
   /// Sets the alert.
   SlideStyler alert(MarkdownAlertStyler value) {
     return merge(SlideStyler(alert: value));
@@ -571,6 +589,7 @@ class SlideStyler extends MixStyler<SlideStyler, SlideSpec> {
       img: MixOps.merge($img, other?.$img),
       link: MixOps.merge($link, other?.$link),
       textScaleFactor: MixOps.merge($textScaleFactor, other?.$textScaleFactor),
+      blockSpacing: MixOps.merge($blockSpacing, other?.$blockSpacing),
       alert: MixOps.merge($alert, other?.$alert),
       horizontalRuleDecoration: MixOps.merge(
         $horizontalRuleDecoration,
@@ -608,6 +627,7 @@ class SlideStyler extends MixStyler<SlideStyler, SlideSpec> {
       img: MixOps.resolve(context, $img),
       link: MixOps.resolve(context, $link),
       textScaleFactor: MixOps.resolve(context, $textScaleFactor),
+      blockSpacing: MixOps.resolve(context, $blockSpacing),
       alert: MixOps.resolve(context, $alert),
       horizontalRuleDecoration: MixOps.resolve(
         context,
@@ -648,6 +668,7 @@ class SlideStyler extends MixStyler<SlideStyler, SlideSpec> {
       ..add(DiagnosticsProperty('img', $img))
       ..add(DiagnosticsProperty('link', $link))
       ..add(DiagnosticsProperty('textScaleFactor', $textScaleFactor))
+      ..add(DiagnosticsProperty('blockSpacing', $blockSpacing))
       ..add(DiagnosticsProperty('alert', $alert))
       ..add(
         DiagnosticsProperty(
@@ -681,6 +702,7 @@ class SlideStyler extends MixStyler<SlideStyler, SlideSpec> {
     $img,
     $link,
     $textScaleFactor,
+    $blockSpacing,
     $alert,
     $horizontalRuleDecoration,
     $blockquote,
diff --git a/packages/superdeck/lib/src/styling/default_style.dart b/packages/superdeck/lib/src/styling/default_style.dart
index f46acb95..c483fe6e 100644
--- a/packages/superdeck/lib/src/styling/default_style.dart
+++ b/packages/superdeck/lib/src/styling/default_style.dart
@@ -80,6 +80,8 @@ SlideStyler _createDefaultSlideStyle() {
   }
 
   return SlideStyler(
+    blockSpacing: 12,
+
     h1: TextStyler()
         .style(
           TextStyleMix(
diff --git a/packages/superdeck/test/goldens/decorated_block_frame.png b/packages/superdeck/test/goldens/decorated_block_frame.png
index 91f7d6dc..9a0abae1 100644
Binary files a/packages/superdeck/test/goldens/decorated_block_frame.png and b/packages/superdeck/test/goldens/decorated_block_frame.png differ
diff --git a/packages/superdeck/test/goldens/inset_slide_container.png b/packages/superdeck/test/goldens/inset_slide_container.png
index 25d1fc21..97c66cc2 100644
Binary files a/packages/superdeck/test/goldens/inset_slide_container.png and b/packages/superdeck/test/goldens/inset_slide_container.png differ
diff --git a/packages/superdeck/test/goldens/plain_markdown_slide.png b/packages/superdeck/test/goldens/plain_markdown_slide.png
index 6abd62b6..96c92f11 100644
Binary files a/packages/superdeck/test/goldens/plain_markdown_slide.png and b/packages/superdeck/test/goldens/plain_markdown_slide.png differ
diff --git a/packages/superdeck/test/goldens/section_two_blocks.png b/packages/superdeck/test/goldens/section_two_blocks.png
index e7a27830..bdc4219e 100644
Binary files a/packages/superdeck/test/goldens/section_two_blocks.png and b/packages/superdeck/test/goldens/section_two_blocks.png differ
diff --git a/packages/superdeck/test/helpers/fake_slide_capture_service.dart b/packages/superdeck/test/helpers/fake_slide_capture_service.dart
index 7323d87e..e584d1cc 100644
--- a/packages/superdeck/test/helpers/fake_slide_capture_service.dart
+++ b/packages/superdeck/test/helpers/fake_slide_capture_service.dart
@@ -28,6 +28,7 @@ class FakeSlideCaptureService extends SlideCaptureService {
     SlideCaptureQuality quality = SlideCaptureQuality.thumbnail,
     required SlideConfiguration slide,
     required BuildContext context,
+    bool includeDebugLayout = false,
   }) async {
     captureCalls++;
     capturedKeys.add(slide.key);
diff --git a/packages/superdeck/test/src/capture/thumbnail_capture_timing_test.dart b/packages/superdeck/test/src/capture/thumbnail_capture_timing_test.dart
index fcbf2de0..24f0427d 100644
--- a/packages/superdeck/test/src/capture/thumbnail_capture_timing_test.dart
+++ b/packages/superdeck/test/src/capture/thumbnail_capture_timing_test.dart
@@ -234,6 +234,30 @@ void main() {
       });
     });
 
+    testWidgets('only includes debug layout guides when requested', (
+      tester,
+    ) async {
+      final context = await _pumpContext(tester);
+      final slide = _slide('debug-layout', '# Layout guides');
+      final capture = SlideCaptureService();
+
+      await tester.runAsync(() async {
+        final cleanBytes = await capture.capture(
+          quality: SlideCaptureQuality.good,
+          slide: slide,
+          context: context,
+        );
+        final debugBytes = await capture.capture(
+          quality: SlideCaptureQuality.good,
+          slide: slide,
+          context: context,
+          includeDebugLayout: true,
+        );
+
+        expect(cleanBytes, isNot(equals(debugBytes)));
+      });
+    });
+
     testWidgets('waits longer for asynchronous image widget content', (
       tester,
     ) async {
diff --git a/packages/superdeck/test/src/styling/components/slide_test.dart b/packages/superdeck/test/src/styling/components/slide_test.dart
new file mode 100644
index 00000000..4f7f50a2
--- /dev/null
+++ b/packages/superdeck/test/src/styling/components/slide_test.dart
@@ -0,0 +1,52 @@
+import 'package:flutter_markdown_plus/flutter_markdown_plus.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:superdeck/superdeck.dart';
+import 'package:superdeck_core/superdeck_core.dart';
+
+import '../../../helpers/slide_test_harness.dart';
+
+void main() {
+  TestWidgetsFlutterBinding.ensureInitialized();
+
+  group('SlideSpec markdown spacing', () {
+    test('disables flutter_markdown_plus implicit block spacing', () {
+      expect(const SlideSpec().toStyle().blockSpacing, 0);
+    });
+
+    testWidgets('default slide style owns the block spacing', (tester) async {
+      await SlideTestHarness.pumpSlide(
+        tester,
+        Slide(
+          key: 'markdown-spacing',
+          sections: [
+            SectionBlock([ContentBlock('## Heading\n\nParagraph')]),
+          ],
+        ),
+      );
+
+      final markdown = tester.widget<MarkdownBody>(find.byType(MarkdownBody));
+      final heading = tester.getRect(find.text('Heading'));
+      final paragraph = tester.getRect(find.text('Paragraph'));
+
+      expect(markdown.styleSheet!.blockSpacing, 12);
+      expect(paragraph.top - heading.bottom, closeTo(24, 0.1));
+    });
+
+    testWidgets('deck styles can override the default spacing', (tester) async {
+      await SlideTestHarness.pumpSlide(
+        tester,
+        Slide(
+          key: 'custom-markdown-spacing',
+          sections: [
+            SectionBlock([ContentBlock('## Heading\n\nParagraph')]),
+          ],
+        ),
+        style: defaultSlideStyle.merge(SlideStyler(blockSpacing: 20)),
+      );
+
+      final markdown = tester.widget<MarkdownBody>(find.byType(MarkdownBody));
+
+      expect(markdown.styleSheet!.blockSpacing, 20);
+    });
+  });
+}