Also works in all JetBrains IDEs: IntelliJ IDEA, RubyMine, WebStorm, PhpStorm, PyCharm.

Installation
- Copy the
.iclsfile intocolorssubfolder of your IDE settings folder (e.g.,~/Library/Preferences/PhpStorm2017.3/colors) — you may need to create it. - Restart your IDE.
- Go to Preferences → Editor → Colors & Fonts.
- Choose “Squirrelsong” from the Scheme dropdown menu.
Customization
How to disable color gradient on main toolbar
- Open Settings.
- Select Appearance & Behavior → Appearance.
- Uncheck Use project colors in the main toolbar.