Flèche

A GNOME 3.10 theme for GNOME Shell, GTK 3, Mutter, GNOME Terminal, and Firefox. See the preview.

Installation

Put the entire repository in /usr/share/themes/
You can then use the Tweak Tool to set the themes.
It is safe to remove the firefox.css and gnome-terminal.xml files from the directory.

Install the Stylish extension.
Install the FXChrome theme.
Go to your Add-ons Manager, select the User Styles page and then write a new style.
Give the style a name and paste the contents of firefox.css.
This style works well with the Movable Firefox Button, Favicon Restorer, and Hide Tabbar extensions.

Download the gnome-terminal.xml file and run the following command: gconftool-2 --load gnome-terminal.xml. Keep in mind that this will erase your previous settings.
Set the profile to "fleche" by right-clicking on your terminal window and choosing it from the Profiles menu.

This theme is not complete yet, and still has bugs. If you find any, please use the issues tracker!
A very slightly modified version of Adwaita is included as GTK 2 theme, to avoid the default fallback. A GTK 2 theme will be made... eventually.
The GNOME Shell theme uses Helvetica Neue. If you do not have it installed, it will use Arimo as fallback; you can get the font here. You can also change the font to your liking in the gnome-shell.css file.
The GNOME Terminal theme includes several profiles, from which you can choose in the Profile settings.