Installare Orta Theme

sudo add-apt-repository ppa:nikount/orta-desktop
sudo apt-get update
sudo apt-get install orta-theme

sudo add-apt-repository ppa:tiheum/equinox

sudo apt-get update && sudo apt-get install faenza-icon-theme

Cambiare dimensione delle icone:

You can change it yourself, if you installed the theme manually goto
~/.themes/Orta/gtk-2.0/
and if you have installed it via ppa goto
/usr/share/themes/Orta/gtk-2.0/
and open the gtkrc file you will find there. At line 13 you will find this :
gtk-icon-sizes = "panel-menu=22,22:gtk-button=16,16"
change it to this :
gtk-icon-sizes = "panel-menu=16,16:gtk-button=16,16"
save the file and reload the theme.