This Firefox Add-on "NASA Night Launch" is a theme/skin for your firefox browser. Although there are literally hundreds if not thousands to choose from, I have this one "NASA Night Launch" becuase I like the black color and the detail to font color and clearly are really good.

Dark Theme for Firefox. Inspired by the night launch of STS-116.

https://addons.mozilla.org/en-US/firefox/addon/4908