Update 1.2: I updated the theme with several improvements including alpha support to Unity. This 1.2 version is the "Edge" Version. Due to changes in gtk engine in gnome 3.11+ this theme suffer from a bug that cut-off the buttons. A complete rewrite based on Adwaita theme is needed, since Numix also suffer from this. Be patient, I will port all the stuff according to the new stuff and luckily in some short time I'll get a new version 2. Cheers. Oh, just in case it is not clear, until that major rewrite, this work will be freezed.
This theme is for Gnome 3.10 environments. The version 1.0-1.2 works well / was tested on Gnome-Shell ONLY. So the "1.0" stable versioning is valid ONLY for Gnome 3.10+ desktops. All the other enviroments are in alpha stage. Unity support will come in the next immediate version 1.1 (which is already available in the Blumix-Edge repo thanks to Sadi -thanks man!-). It wasn't tested in cinnamon, xfce, lxde, etc... If you want to try it, do it KNOWING you MAY find weard things... please report them in order to improve the theme! :) Cheers!
Blumix Gtk Theme: Simple. Rounded. Essential. Started as a minimal Blue-ish Mod for Numix Gtk3 Theme, now, with some perspective, it's growing with its own identity. It supports gtk3.10, gtk3.6, gtk2and metacity3. Oh, yeah. The metacity is intend to be like that: minimal. Mouse over to see the buttons. :)
This work is an updated, newer, better, nicer, and more complete version of my previous work http://gnome-look.org/content/show.php/%5BGtk+3.8+3.10+Theme%5D+Blumix+V0.21?content=161811
Featuring Plank Themer. So give it a try if you want. :) http://rhoconlinux.github.io/plank-themer/index.html
Bleeding edge version of this theme: https://github.com/rhoconlinux/Blumix-Edge/tree/master/Blumix-Edge. Try it to see the latest developments.
UBUNTU RECOMMENDED INSTALL
You can install it through a Ninja-Install, one command to apply it. In Ubuntu and derivatives open a terminal and run (will download, install and apply the theme):
mkdir -p ~/blumix-install && cd ~/blumix-install && wget https://github.com/rhoconlinux/Blumix/archive/master.zip && unzip master.zip && cd Blumix-master && sudo cp -a Blumix /usr/share/themes/Blumix1.0 && gsettings set org.gnome.desktop.interface gtk-theme "Blumix1.0" && gsettings set org.gnome.desktop.wm.preferences theme 'Blumix1.0' && cd ~ && rm -R ~/blumix-install/Oh, and dont forget to leave your impression by voting if everything went ok. :)
Install the dependences!!! Otherwise it will not work right:
sudo apt-get install -y gtk2-engines-murrine gtk2-engines-pixbuf gtk3-engines-unico
This means the theme requires murrine, pixbuf and unico engines installed on your system. If you do not have them, Firefox, Thunderbird, Libreoffice and other gtk2 programs will not draw the theme (and you will get a win95 look).
Download the file. Once you got it, uncompress the zip. Browse the uncompressed content and copy the folder named Blumix in /usr/share/themes/ (this will require root access). Apply it with your favourite tunning tool (gnome-tweaks, unity-tweak, ubuntu-tweak... etc.). If you can't see properly some apps read the note above... probably you should install the required engines to make it work. You can also pass by and give a like in deviant-art and fork/clone it in github if you feel so. If you see anything odd, please report a bug (in github) or drop a comment down there.
Full Review and Screenshots https://rhoconlinux.wordpress.com/2014/02/13/blumix-1-0-actualizado-el-tema-gtk3-10-minimalismo-nuevo/ (in spanish)
Project on Github: https://github.com/rhoconlinux/Blumix#blumix-gtk310-
Oh! and remember to vote if you liked it. This is a work made with love, for sharing. So please be kind and share your critics, comments, impressions down there!. :)