I try to pick templates that have the general geometry (including margins and paddings) that I'm going for. I use the "no margin all" and "no padding all" particle variations all the time. I generally have an area in my custom.scss file that I title "theme overrides" where I have global CSS overrides for pieces of the theme I want to change. Rarely, but still on occasion, I'll change certain values in the core SCSS files (typography.scss, configuration.scss, buttons.scss, etc) as needed.
Gantry's grid system only has 1 breakpoint that matters... the mobile only breakpoint where things get stacked into 1 column... on occassion I want the desktop or tablet breakpoint to show 2 columns instead of 4 or 3 columns instead of 6... I'll use the breakpoint mixins in a custom.scss file to target a custom-class.g-block.size-25 to be 50% instead of 25% for example to get better responsive columns at different breakpoints. Or more often I find myself wanting 2 columns for certain things on mobile so I'll do something like:
@include breakpoint(mobile-only) {
custom-class.g-block{
width: 50%;
}
}
docs.gantry.org/gantry5/tutorials/media-...queries-on-your-site