diff --git a/README.md b/README.md
index 8c518526..32f14b4a 100644
--- a/README.md
+++ b/README.md
@@ -15,7 +15,7 @@ The local server allows to run the editor and the documentation from your comput
 
 The following commands are a 1-time setup after synching the repo on your machine.
 
-* if not yet installed, install [Node.js 4.4.5 or higher](https://nodejs.org/en/download/)
+* See requirements for [pxt](https://github.com/Microsoft/pxt)
 * [clone this repo](https://help.github.com/articles/cloning-a-repository/) to your computer and go in the project folder
 ```
 git clone https://github.com/microsoft/pxt-microbit
diff --git a/sim/visuals/microbit.ts b/sim/visuals/microbit.ts
index d315fc12..116ac6d9 100644
--- a/sim/visuals/microbit.ts
+++ b/sim/visuals/microbit.ts
@@ -712,8 +712,9 @@ namespace pxsim.visuals {
                     tiltDecayer = 0;
                 }
 
-                let ax = (ev.clientX - this.element.clientWidth / 2) / (this.element.clientWidth / 3);
-                let ay = (ev.clientY - this.element.clientHeight / 2) / (this.element.clientHeight / 3);
+                let bbox = this.element.getBoundingClientRect();
+                let ax = (ev.clientX - bbox.width / 2) / (bbox.width / 3);
+                let ay = (ev.clientY - bbox.height / 2) / (bbox.height / 3);
 
                 let x = - Math.max(- 1023, Math.min(1023, Math.floor(ax * 1023)));
                 let y = Math.max(- 1023, Math.min(1023, Math.floor(ay * 1023)));