title: PNG or ICO used as favicon lacks transparency (IE/Edge)
body: <p>I've noticed that some favicon's for web-pages (including my own) does not display correctly and transparency is ignored.</p>
  
  <p>For example: <a href="https://i.stack.imgur.com/xT4IO.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/xT4IO.png" alt="enter image description here"></a></p>
  
  <p>Feel free to test my <a href="http://bdu.bz/" rel="nofollow noreferrer">web-page</a> favicon out using IE/Edge and it will display similar results. I have made sure that transparency has been exported (in the alpha layer) using GIMP. An image is attached below for reference. </p>
  
  <p><a href="https://i.stack.imgur.com/eb11w.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/eb11w.png" alt="enter image description here"></a></p>
  
  <p>Does anyone see anything wrong with either my header coding for a favicon or an issue with the image?</p>
  
  <pre><code>&lt;link rel="icon" type="image/x-icon" href="./favicon.ico?v=1.0"&gt;
  </code></pre>