Hack Chrome to show its internal pages with black background

Solution 1:

You could theme your Chrome internal pages by utilizing the user stylesheet found at:

On Windows

C:\Users\Username\AppData\Local\Google\Chrome\User Data\Default\User StyleSheets\Custom.css

On OSX

~/Library/Application Support/Google/Chrome/Default/User StyleSheets/Custom.css

On Ubuntu

~/.config/chromium/Default/User StyleSheets/Custom.css

If it doesn't exist yet, create it.

If you simply put the following CSS into it:

#card-slider-frame {
  background : black;
  color      : white !important;
}

Your New Tab page will look more like this:

I also found the suggestion to create an extension that controls the theme of the new tab page. This might be more reliable, as the Custom.css styles are applied to all internal and external pages.