title: Hide top bar when scrolling down
body: <p>how can I obtain same or similar result to top bar in Google Keep app (Android) - which is always on and if we scroll down its hides. Similar is done in Chrome browser on Android.</p>
  
  <p>It appear again when scrolling up.</p>
  
  <p><a href="http://img542.imageshack.us/img542/5980/unnamedap.jpg" rel="nofollow noreferrer">Valid XHTML http://img542.imageshack.us/img542/5980/unnamedap.jpg</a></p>