Favicon needs some contrast.

Using black-dark skin on the browser, makes the favicon almost-invinsible. Icons supposed to be seen. It's not that big of a deal but it's not that big of a hustle either. It needs a contrasting color to make it visible. Something like the Old Favicon.Keep the black square and add it on a greyish-silverish box or make it silver square in a black box.
Dark Browser Skin
Bright Browser Skin
*Favicon is the icon that the site displays on the bookmark bar and on the opened tab. In case someone doesn't know what it is.