Welcome to Smogon! Take a moment to read the Introduction to Smogon for a run-down on everything Smogon, and make sure you take some time to read the global rules.
I made a darker version of Pokemon Showdown
Preview:
You can get it here: http://userstyles.org/styles/87532/pokemon-showdown-dark?r=1368592858
Just be sure to have the addon called "Stylish" installed.