I came across this cool add-on, you can pimp out any site to your liking. Sample:
Here is link: https://addons.mozilla.org/en-US/firefox/addon/color-that-site/?src=search
About this Add-on
The purpose of this Add-on is to let you easily change the colors of any web site you want. These color edits can be permanently saved and be im-/exported for sharing.
• Perhaps you want to get an impression of how your own site looks like in different colors.
• .. or the color set of a specific site/page causes headaches. Why not change it?
• .. or you simply like to experiment.
Start up this add-on when you like to change the colors of a site. Then press the button [Go!] and change the colors for Foreground (Text) and Background with some dials.
'Under the hood' this Add-On does (apparently) more: It overrides the CSS of a site and uses a number of "tricks" to be as complete as possible. Also image processing and re-encoding is done to change the color of (background-)images.
• On complex sites with many background images this add-on might need much memory while editing.
• Contents which use plugins like Flash or PDF files can not be changed.
• Whether color edits on one web page apply to the whole site or not, depends on the sites CSS structure. But multiple edits can be applied to different pages/folders of the site.