scroll demo tweak

examples/scroll.html

@@ -92,7 +92,9 @@
             <h2>Image Backgrounds</h2>
           </section>
           <section data-background-video-muted data-background-video="https://s3.amazonaws.com/static.slid.es/site/homepage/v1/homepage-video-editor.mp4,https://s3.amazonaws.com/static.slid.es/site/homepage/v1/homepage-video-editor.webm">
-            <h2>Video background</h2>
+            <div style="background-color: rgba(0, 0, 0, 0.9); color: #fff; padding: 20px;">
+              <h2>Video background</h2>
+            </div>
           </section>
         </section>
 				<section><h2>The end</h2></section>