I would like to share with you the 2.x version of my themes for FreeCAD.
The styles have been totally rewritten from scratch from all the experience I took on version 1 series, that's the main reason I have created a new thread instead of using the previous one.
Basically, the themes are 2: Dark and Light, with 3 variations each (green, blue and orange). It's really easy to switch/tweak colors if you know a little bit of CSS: I have tested them on OSX, Windows and Ubuntu so they should work on any other OS, anyway, let me know if you find bugs or glitches.
Some comments about FreeCAD and theming:
- They are designed for FreeCAD 0.16 but they will work on current stable 0.15 but you will need to read the installation notes in order to fix some things
If you are using a previous v0.16 development version, v0.15 or older you will need you download them manually:
Download (install instructions)
FreeCAD Dark and Light stylesheets v2.03
- simplified toolbar button separators
- added hover and pressed states for toolbar buttons to improve user experience
- partial fix for button with icons inside Task panel
- fixed styles for fields inside a table cell
FreeCAD Dark and Light stylesheets v2.02
- fixed background logo for Win and Linux
- improved QToolBar handle for different icon sizes (selectable by user inside Preferences)
- tweaked editable fields inside QToolBar in order to work for all icon sizes (selectable by user inside Preferences)
- fixed Ubuntu problem that caused a blank line inside up/down buttons of QSpinBox and similar
- tweaked Python Editor color for Light theme
- fixed buttons margin/padding inside Task tab
- tweaked color for checked QPushButtons inside Draft WB for better user experience
- solved Ubuntu outline on some selected items
- inverted Progress bar colors (now dark is at bottom)
- lightened scrollbar default and hover colors
- restyled Preferences Icon List default and hover states
- reseted QListView hover on Windows
- fixed and styled Text/Python editor
- totally redone from scratch
- code simplified
- code ordered by element
- almost everything commented
- improved the overall look of the GUI in order to match any OS
- tweaked colors for a better experience
- solved lots of bugs and minor issues
Source
GitHub
I hope you like them

If you feel like this should be on master, please, let me know and I will try a pull request.
Cheers