I'm new to gantry5, but I can't get work the custom.css tutorial work on hydrogen template and overriding bootstrap-gantry.css located on media/gantry5/assets/css.
Sorry but no.
I've an unsolved php 5.4 requeriment in my VPS...webs still running 5.3.29 and I can't post the web because gantry 5 uses 5.4 minimum.
:/