A few months ago I wrote a tiny but fine plugin for IDA Pro allowing to theme everything that cannot be themed using IDA’s built-in color-settings. It comes with a dark theme intended to be combined with the idaConsonance IDA color theme by default, however custom themes can be created using Qt-stylesheets. You can find some information about creating themes on the GitHub project page.
IDAPro with idaConsonance IDASkins disabled
IDAPro with idaConsonance and IDASkins enabled
For installation, just drop the contents of either ida_qt_4.7.2 (IDA 6.0 and 6.1) OR ida_qt_4.8.4 (IDA >= 6.2) into your IDA installation root. All versions of IDA starting with 6.0 are supported and should work. If you encounter any problems, feel free to report issues on GitHub or leave a comment.