Thread watcher

A few minor changes to make the thread watcher prettier.

I can't figure out how to properly test it, but the code looks fine and runs in the console.
https://developer.mozilla.org/en-US/docs/Web/API/Window.getComputedStyle
http://www.w3.org/TR/DOM-Level-2-Style/css.html#CSS-CSSview-getComputedStyle