The same style is available with options for background colors and background texture or images: http://freestyler.ws/style/39631/youtube-black-2013

If you want to hide channel backgrounds you can use http://freestyler.ws/style/76961/youtube-hide-channel-backgrounds.

I appreciate all feedback and don't consider it a "complaint" if somebody has a suggestion. I want this style to be compatible with YouTube Center and YousableTubeFix (and hopefully other scripts and styles) so I am interested in knowing about any incompatibilities as well.

The dark scrollbars are based on userstyles's userstyles's Eli (Ukiss) & Sungyeol (Infinite) by makondo@userstyles.

Updates:

2014-06-12: removed white borders on player description area
2014-04-24: fixes for YouTube update: white background of video names and descriptions
2014-02-21,28: fixes for new layout
2014-02-18: misc
2014-01-29: expanded menu fix, also icons on watch page
2013-12-06: misc minor improvements
2013-11-19: fixed homepage/subscription-feed-page problem seeing/accessing guide and recommended channels, fixed some white areas in video editing pages
2013-11-07: fixed new comment section