The HTML5 full screen API is unavailable.
( ᵒ̴̶̷̥́ _ᵒ̴̶̷̣̥̀ )

Either :

• Your browser does not support it (Safari on iOS for instance)
• This demo is embedded in an iframe that does not allow full screen mode.
  It must have the 'allowfullscreen', 'webkitallowfullscreen' and/or 'mozallowfullscreen' attributes in order to work.
  
  You can find the demo here (no iframe involved) or a working iframe demo there.

<fullscreen-icon-button>

The simplest <fullscreen-icon-button>, takes care of everything for you

<fullscreen-icon-button> can be styled using all the mixins from <paper-icon-button>

<fullscreen-icon-button> and <fullscreen-api> can automatically find the element to be displayed full screen if you set a selector to their `target` attribute

<fullscreen-api>

<fullscreen-api> is not a dom module, thus offering you a lot of flexibility