Tested on Roundcube 1.2-beta
Mabola is a clean and usable skin for latest Roundcube Webmail (http://roundcube.net). Is based on Material Design, Bootstrap and inherits from Larry Skin, so there should be no unstyled content.
It supports Threecol plugin. Check it out at EstudioNexos/threecol.
Icons are from https://github.com/laclasse-com/roundcube_laclasse_skin.
Screenshots at http://www.estudionexos.com/mabola-skin-for-roundcube.html
LICENSE for Laclasse Icons:
The contents of this folder are subject to the Creative Commons Attribution-ShareAlike License. It is allowed to copy, distribute, transmit and to adapt the work by keeping credits to the original autors in the README file. See http://creativecommons.org/licenses/by-sa/3.0/ for details.