diff --git a/shader.html b/shader.html
index a20719d..5fd07f9 100644
--- a/shader.html
+++ b/shader.html
@@ -6,8 +6,6 @@
         position: fixed;
         pointer-events: none;
         image-rendering: pixelated;
-        width: 100%;
-        height: 100%;
       }
 
       .canvas-small {
@@ -20,6 +18,8 @@
       .canvas-fullscreen {
         top: 0;
         left: 0;
+        width: 100%;
+        height: 100%;
       }
     </style>
     <script>
diff --git a/src/shader.js b/src/shader.js
index 55c4690..da0d0c0 100644
--- a/src/shader.js
+++ b/src/shader.js
@@ -300,8 +300,10 @@ export class ShaderSession {
       this.uniforms = this.instance.uniforms;
       if (code.indexOf('// size: fullscreen') > -1) {
         fullscreenCanvas(this.canvas);
+        this.instance.update();
       } else if (code.indexOf('// size: small') > -1) {
         smallCanvas(this.canvas);
+        this.instance.update();
       }
       console.log('Shader updated!');
     } catch (err) {