Your documentation says that for overriding any CSS in t3_bs3_blank we should use the custom.css file in the css folder for the t3_ bs3_blank template.
However, for my theme called "vif", created in ThemeMagic, I want to add some custom variables. I know how to use LESS and would like to do my overrides in a LESS file, and have several colors I want to assign to variables.
What file would I use to create my theme's LESS file? There are several blank files in the themes/vif folder. How would I go about putting in more CSS into my theme file using LESS and variables?