diff --git a/src/lib/components/CanvasView.svelte b/src/lib/components/CanvasView.svelte
index 35ad5a6..ad72c68 100644
--- a/src/lib/components/CanvasView.svelte
+++ b/src/lib/components/CanvasView.svelte
@@ -15,7 +15,7 @@
 	import { dirName, displayName } from '$lib/storage/vault.svelte';
 	import { bounds, intersects, rectBeside, type Rect } from '$lib/model/layout';
 	import { canInsert, freeSlots, freeSlotsOf, neighbor, type Dir, type Slot } from '$lib/model/tree';
-	import { PAGE_PRESETS, type Stroke } from '$lib/model/types';
+	import { A4, PAGE_PRESETS, type Stroke } from '$lib/model/types';
 	import { PalmRejector } from '$lib/ink/palm';
 	import { StrokeRecorder, hitStroke } from '$lib/ink/stroke';
 	import { pageCssVars } from '$lib/editor/pageStyle';
@@ -107,7 +107,7 @@
 		const a = doc.rectOf(slot.anchor);
 		if (!a) return null;
 		const page = doc.pages[slot.anchor];
-		const s = size ?? (page && !page.origin ? { width: page.width, height: page.height } : { width: 595.28, height: 841.89 });
+		const s = size ?? (page ? { width: page.width, height: page.height } : A4);
 		return rectBeside(a, slot.dir, s);
 	}
 
diff --git a/src/lib/state/doc.svelte.ts b/src/lib/state/doc.svelte.ts
index 53900df..4780fa2 100644
--- a/src/lib/state/doc.svelte.ts
+++ b/src/lib/state/doc.svelte.ts
@@ -161,8 +161,8 @@ export class CanvasDoc {
 
 	addBlankPage(anchor: string, dir: Dir): string | null {
 		const a = this.pages[anchor];
-		// New pages default to A4, oriented like their neighbour when it's a plain page.
-		const size = a && !a.origin && a.width > a.height ? { width: A4.height, height: A4.width } : A4;
+		// New pages inherit the size of the page they grow from (A4 if it's missing).
+		const size = a ? { width: a.width, height: a.height } : A4;
 		const id = newId();
 		return this.insertPages(anchor, dir, [{ id, ...size, markdown: '', strokes: [] }]) ? id : null;
 	}