Change Dock color on left/right site in OS X 10.9 Mavericks

New in OS X Mavericks, when using the famous dock on the left or right site:
It has a white background now. It makes it hard to see the icons and the design is awful.

Does anyone know how to change it back to the old black and transparent style?
(in the screenshot on the left side)

Same Topic available on apple boards:
https://discussions.apple.com/thread/5469133

Solution 1:

You can set hide-mirror to true to remove the blur effect:

defaults write com.apple.dock hide-mirror -bool true;killall Dock

Before: After:

I don't know how to make the background dark though.

Solution 2:

There's a third-party utility app called cDock that can change or remove the Dock's background. I can confirm it works for me on OS X 10.9.2. Just download it, run and select the "Install Transparent dock" option. You can also choose the "Install 10.8 style dock" option which will enable the theme from OS X 10.8. You can revert to the default dock at any time by running the app again and selecting the "Restore Dock" option.