Add checks for meta: name="theme-color"

[teinett]

There is meta tag theme-color for color of browser tab: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta/name/theme-color

Could you add checks for this meta tag, please?

<meta name="theme-color" content="#4285f4" />
<meta name="theme-color" media="(prefers-color-scheme: light)" content="cyan" />
<meta name="theme-color" media="(prefers-color-scheme: dark)" content="black" />

There should be two checks:

1) the presence of the meta-tag 2) show the color

[patrick91]

@teinett done in 0.3.0 :)