diff --git a/src/windy/platforms/emscripten/platform.nim b/src/windy/platforms/emscripten/platform.nim
index 0e09c4c..af72ed7 100644
--- a/src/windy/platforms/emscripten/platform.nim
+++ b/src/windy/platforms/emscripten/platform.nim
@@ -110,9 +110,10 @@ proc pollEvents*() =
   emscripten_sleep(0)
 
 proc size*(window: Window): IVec2 =
-  # Get the size of the canvas.
-  result.x = get_window_width() * get_device_pixel_ratio().int32
-  result.y = get_window_height() * get_device_pixel_ratio().int32
+  # Get the size of the canvas in physical pixels (CSS size × DPR).
+  let dpr = get_device_pixel_ratio()
+  result.x = (get_window_width().float32 * dpr).int32
+  result.y = (get_window_height().float32 * dpr).int32
 
 proc `size=`*(window: Window, size: IVec2) =
   ## Size cannot be set on emscripten windows.
@@ -193,14 +194,11 @@ proc `focused=`*(window: Window, focused: bool) =
   discard  # Focus is controlled by browser
 
 proc updateCanvasSize(window: Window) =
-  let
-    width = get_window_width().int32
-    height = get_window_height().int32
-    contentScale = get_device_pixel_ratio().float32
-    size = ivec2(width, height)
+  ## Update canvas size to match window dimensions scaled by device pixel ratio.
+  let dpr = get_device_pixel_ratio()
   set_canvas_size(
-    (size.x.float32 * contentScale).int32,
-    (size.y.float32 * contentScale).int32
+    (get_window_width().float32 * dpr).round().int32,
+    (get_window_height().float32 * dpr).round().int32
   )
 
 proc contentScale*(window: Window): float32 =