title: Add way to go full screen in new Unity WebGL template
body: <p>Generally speaking, when working with Unity WebGL builds, the default template looks like this</p>
  <p><a href="https://i.stack.imgur.com/OF2rB.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/OF2rB.png" alt="Unity default WebGL build" /></a></p>
  <p>From the <a href="https://docs.unity3d.com/Manual/webgl-templates.html" rel="nofollow noreferrer">documentation</a>, we can see that when we want to use WebGL templates in Unity we have to create a folder in Assets named <strong>WebGLTemplates</strong>, and a folder named New Template (or whatever name you will) and add an <strong>index.html</strong> there.</p>
  <p><a href="https://i.stack.imgur.com/mQThX.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/mQThX.png" alt="Unity WebGL New Template" /></a></p>
  <p>Also, the index.html should have a code similar to this</p>
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html lang=&quot;en-us&quot;&gt;
  
    &lt;head&gt;
      &lt;meta charset=&quot;utf-8&quot;&gt;
      &lt;meta http-equiv=&quot;Content-Type&quot; content=&quot;text/html; charset=utf-8&quot;&gt;
      &lt;title&gt;Unity WebGL Player | %UNITY_WEB_NAME%&lt;/title&gt;
      &lt;script src=&quot;%UNITY_WEBGL_LOADER_URL%&quot;&gt;&lt;/script&gt;
      &lt;script&gt;
      var unityInstance = UnityLoader.instantiate(&quot;unityContainer&quot;, &quot;%UNITY_WEBGL_BUILD_URL%&quot;);
      &lt;/script&gt;
    &lt;/head&gt;
    
    &lt;body&gt;
      &lt;div id=&quot;unityContainer&quot; style=&quot;width: %UNITY_WIDTH%px; height: %UNITY_HEIGHT%px; margin: auto&quot;&gt;&lt;/div&gt;
    &lt;/body&gt;
    
  &lt;/html&gt;
  </code></pre>
  <p>Then, under Player settings, select that template</p>
  <p><a href="https://i.stack.imgur.com/tY0fi.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/tY0fi.png" alt="Unity WebGL Build new template" /></a></p>
  <p>Thing is, this doesn't come with the option to increase to full-size.</p>
  <p><a href="https://i.stack.imgur.com/DXmX2.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/DXmX2.png" alt="Unity New Template without the button to increase size to fullscreen" /></a></p>