diff -r b371d4b36bf9 qt/ScintillaEditBase/ScintillaQt.cpp
--- a/qt/ScintillaEditBase/ScintillaQt.cpp	Sat Mar 07 10:27:10 2026 +1100
+++ b/qt/ScintillaEditBase/ScintillaQt.cpp	Sat Mar 07 10:55:12 2026 +1100
@@ -804,6 +804,13 @@
 	PRectangle rcClient = GetClientRectangle();
 	paintingAllText = rcPaint.Contains(rcClient);
 
+	QWidget *device = static_cast<QWidget *>(wMain.GetID());
+	const qreal scale = device->devicePixelRatioF();
+	// Including 1.5 as unscaled to demonstrate seaming
+	bool scaled = !(scale == 1.0 || scale == 2.0 || scale == 1.5);
+
+	vs.seamOverDraw = (scaled && !view.bufferedDraw && view.LinesOverlap()) ? 1.0 : 0.0;
+
 	AutoSurface surfacePaint(this);
 	Paint(surfacePaint, rcPaint);
 	surfacePaint->Release();
diff -r b371d4b36bf9 src/EditView.cxx
--- a/src/EditView.cxx	Sat Mar 07 10:27:10 2026 +1100
+++ b/src/EditView.cxx	Sat Mar 07 10:55:12 2026 +1100
@@ -931,7 +931,7 @@
 	}
 	const bool drawEOLSelection = eolInSelection && vsDraw.selection.eolFilled && (line < model.pdoc->LinesTotal() - 1);
 
-	const PRectangle rcArea = Clamp(rcLine, Edge::left, left);	// Limit to right side of line from 'left'
+	const PRectangle rcArea = vsDraw.ApplySeam(Clamp(rcLine, Edge::left, left));	// Limit to right side of line from 'left'
 
 	const ColourRGBA selectionBack = drawEOLSelection ? SelectionBackground(model, vsDraw, eolInSelection) : ColourRGBA{};
 	ColourRGBA base = vsDraw.styles[StyleDefault].back;
@@ -1080,9 +1080,9 @@
 			blobsWidth += rcBlob.Width();
 			const ColourRGBA textBack = TextBackground(model, vsDraw, ll, background, eolInSelection, false, styleMain, eolPos);
 			if (drawEOLSelection && (vsDraw.selection.layer == Layer::Base)) {
-				surface->FillRectangleAligned(rcBlob, Fill(selectionBack.Opaque()));
+				surface->FillRectangleAligned(vsDraw.ApplySeam(rcBlob), Fill(selectionBack.Opaque()));
 			} else {
-				surface->FillRectangleAligned(rcBlob, Fill(textBack));
+				surface->FillRectangleAligned(vsDraw.ApplySeam(rcBlob), Fill(textBack));
 			}
 			ColourRGBA blobText = textBack;
 			if (drawEOLSelection && (vsDraw.selection.layer == Layer::UnderText)) {
@@ -1113,9 +1113,9 @@
 	} else if (const Style &styleLast = vsDraw.styles[ll->LastStyle()]; styleLast.eolFilled) {
 		base = styleLast.back;
 	}
-	surface->FillRectangleAligned(rcEOLIsSelected, Fill(base.Opaque()));
+	surface->FillRectangleAligned(vsDraw.ApplySeam(rcEOLIsSelected), Fill(base.Opaque()));
 	if (drawEOLSelection && (vsDraw.selection.layer != Layer::Base)) {
-		surface->FillRectangleAligned(rcEOLIsSelected, selectionBack);
+		surface->FillRectangleAligned(vsDraw.ApplySeam(rcEOLIsSelected), selectionBack);
 	}
 
 	const bool drawEOLAnnotationStyledText = (vsDraw.eolAnnotationVisible != EOLAnnotationVisible::Hidden) && model.pdoc->EOLAnnotationStyledText(line).text;
@@ -1286,7 +1286,7 @@
 		// it may be double drawing. This is to allow stadiums with
 		// curved or angled ends to have the area outside in the correct
 		// background colour.
-		surface->FillRectangleAligned(rcSegment, Fill(textBack));
+		surface->FillRectangleAligned(vsDraw.ApplySeam(rcSegment), Fill(textBack));
 		FillLineRemainder(surface, model, vsDraw, ll, line, rcLine, rcSegment.right, subLine);
 	}
 
@@ -1684,7 +1684,7 @@
 					inIndentation = false;
 				}
 			}
-			surface->FillRectangleAligned(rcSegment, Fill(textBack));
+			surface->FillRectangleAligned(vsDraw.ApplySeam(rcSegment), Fill(textBack));
 			if (!ts.representation) {
 				// Normal text display
 				if (vsDraw.viewWhitespace != WhiteSpace::Invisible) {
@@ -1697,7 +1697,7 @@
 							if (drawWhitespaceBackground && vsDraw.WhiteSpaceVisible(inIndentation)) {
 								const PRectangle rcSpace = Intersection(rcLine,
 									ll->Span(cpos + ts.start, cpos + ts.start + countSpaces).Offset(horizontalOffset));
-								surface->FillRectangleAligned(rcSpace,
+								surface->FillRectangleAligned(vsDraw.ApplySeam(rcSpace),
 									vsDraw.ElementColourForced(Element::WhiteSpaceBack).Opaque());
 							}
 							cpos += countSpaces;
@@ -2520,6 +2520,8 @@
 		double durCopy = 0.0;
 		ElapsedPeriod epWhole;
 #endif
+		// This is temporary to make any scaling seams obvious
+		surface->FillRectangleAligned(rcTextArea, Fill(ColourRGBA(0,0,0)));
 		const bool bracesIgnoreStyle = ((vsDraw.braceHighlightIndicatorSet && (model.bracesMatchStyle == StyleBraceLight)) ||
 			(vsDraw.braceBadLightIndicatorSet && (model.bracesMatchStyle == StyleBraceBad)));
 
@@ -2691,6 +2693,7 @@
 	// Don't show indentation guides
 	// If this ever gets changed, cached pixmap would need to be recreated if technology != Technology::Default
 	vsPrint.viewIndentationGuides = IndentView::None;
+	vsPrint.seamOverDraw = 0;	// Not on screen so don't need screen scaling fix
 	// Don't show the selection when printing
 	vsPrint.selection.visible = false;
 	vsPrint.elementColours.clear();
diff -r b371d4b36bf9 src/ViewStyle.cxx
--- a/src/ViewStyle.cxx	Sat Mar 07 10:27:10 2026 +1100
+++ b/src/ViewStyle.cxx	Sat Mar 07 10:55:12 2026 +1100
@@ -310,6 +310,7 @@
 	whitespaceSize = source.whitespaceSize;
 	viewIndentationGuides = source.viewIndentationGuides;
 	viewEOL = source.viewEOL;
+	seamOverDraw = source.seamOverDraw;
 	extraFontFlag = source.extraFontFlag;
 	extraAscent = source.extraAscent;
 	extraDescent = source.extraDescent;
@@ -762,6 +763,10 @@
 	return (caretStyle <= CaretStyle::Block) ? static_cast<CaretShape>(caretStyle) : CaretShape::line;
 }
 
+PRectangle ViewStyle::ApplySeam(const PRectangle &rc) const noexcept {
+	return PRectangle(rc.left, rc.top, rc.right + seamOverDraw, rc.bottom + seamOverDraw);
+}
+
 void ViewStyle::AllocStyles(size_t sizeNew) {
 	size_t i=styles.size();
 	styles.resize(sizeNew);
diff -r b371d4b36bf9 src/ViewStyle.h
--- a/src/ViewStyle.h	Sat Mar 07 10:27:10 2026 +1100
+++ b/src/ViewStyle.h	Sat Mar 07 10:55:12 2026 +1100
@@ -154,6 +154,7 @@
 	int whitespaceSize;
 	Scintilla::IndentView viewIndentationGuides;
 	bool viewEOL;
+	XYPOSITION seamOverDraw = 0;
 
 	CaretAppearance caret;
 
@@ -246,6 +247,8 @@
 	bool DrawCaretInsideSelection(bool inOverstrike, bool imeCaretBlockOverride) const noexcept;
 	CaretShape CaretShapeForMode(bool inOverstrike, bool isMainSelection) const noexcept;
 
+	PRectangle ApplySeam(const PRectangle &rc) const noexcept;
+
 private:
 	void AllocStyles(size_t sizeNew);
 	void CreateAndAddFont(const FontSpecification &fs);