Stylizing the Header Bar Theme Color in Safari for iOS

In iOS 15 Safari has added the ability to theme the header bar of the web-browser via a meta-tag in the header of your website. For example:

<meta name="theme-color" content="#000000">

You can also pick light / dark mode specific colors by media-query:

<meta name="theme-color" content="#ffffff" media="(prefers-color-scheme: light)">

<meta name="theme-color" content="#000000" media="(prefers-color-scheme: dark)">