diff --git a/emcclib.js b/emcclib.js
index c145426..3d9db2f 100644
--- a/emcclib.js
+++ b/emcclib.js
@@ -546,7 +546,7 @@ mergeInto(LibraryManager.library, {
     js_canvas_set_size: function(w, h) {
         onscreen_canvas.width = w;
         offscreen_canvas.width = w;
-        resizable_div.style.width = w + "px";
+        resizable_div.style.width = w / (window.devicePixelRatio || 1) + "px";
 
         onscreen_canvas.height = h;
         offscreen_canvas.height = h;
diff --git a/html/jspage.pl b/html/jspage.pl
index e19c89a..b9e4249 100755
--- a/html/jspage.pl
+++ b/html/jspage.pl
@@ -257,6 +257,7 @@ EOF
 
 #puzzlecanvas {
     display: block;
+    width: 100%;
 }
 
 #statusbarholder {