diff --git a/particles/particle.playground/Contents.swift b/particles/particle.playground/Contents.swift
index 694d377..912110b 100644
--- a/particles/particle.playground/Contents.swift
+++ b/particles/particle.playground/Contents.swift
@@ -2,7 +2,7 @@
 import MetalKit
 import PlaygroundSupport
 
-let frame = NSRect(x: 0, y: 0, width: 400, height: 400)
+let frame = NSRect(x: 0, y: 0, width: 400, height: 800)
 let delegate = MetalView()
 let view = MTKView(frame: frame, device: delegate.device)
 view.delegate = delegate
diff --git a/particles/particle.playground/Resources/Shaders.metal b/particles/particle.playground/Resources/Shaders.metal
index 0da8ea0..230648a 100644
--- a/particles/particle.playground/Resources/Shaders.metal
+++ b/particles/particle.playground/Resources/Shaders.metal
@@ -14,10 +14,12 @@ float distanceToParticle(float2 point, Particle p) {
 kernel void compute(texture2d<float, access::write> output [[texture(0)]],
                     constant float &time [[buffer(0)]],
                     uint2 gid [[thread_position_in_grid]]) {
-    int width = output.get_width();
-    int height = output.get_height();
+    float width = output.get_width();
+    float height = output.get_height();
     float2 uv = float2(gid) / float2(width, height);
-    float2 center = float2(0.5, time);
+    float aspect = width / height;
+    uv.x *= aspect;
+    float2 center = float2(aspect / 2, time);
     float radius = 0.05;
     float stop = 1 - radius;
     if (time >= stop) { center.y = stop; }
diff --git a/particles/particle.playground/playground.xcworkspace/xcuserdata/mhorga.xcuserdatad/UserInterfaceState.xcuserstate b/particles/particle.playground/playground.xcworkspace/xcuserdata/mhorga.xcuserdatad/UserInterfaceState.xcuserstate
index b1d57fa..861773a 100644
Binary files a/particles/particle.playground/playground.xcworkspace/xcuserdata/mhorga.xcuserdatad/UserInterfaceState.xcuserstate and b/particles/particle.playground/playground.xcworkspace/xcuserdata/mhorga.xcuserdatad/UserInterfaceState.xcuserstate differ
diff --git a/particles/particle.playground/timeline.xctimeline b/particles/particle.playground/timeline.xctimeline
deleted file mode 100644
index bf468af..0000000
--- a/particles/particle.playground/timeline.xctimeline
+++ /dev/null
@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<Timeline
-   version = "3.0">
-   <TimelineItems>
-   </TimelineItems>
-</Timeline>