Some websites like nytimes.com, twitter.com, cnn.com already have an icon when pinned to the top. According to “What's new in Safari 9” this code should be added in order to provide a custom icon:
<link rel="icon" sizes="any" mask href="website_icon.svg">
<meta name="theme-color" content="red">
That's what I did on our website (obdev.at) but Safari seems to ignore it. Anything I'm missing here? Or is there no support for third-party websites yet?