Minifrontpage css override, where?

Hello
I'm using Monifrontpage module on a J! 2.5.x/Gantry site with "default" style/template.
Where to put exaclty the css file to override the "default" one? I'm a little confused if to put a "themes" or directly a "default" directory into templates/gantry/html/mod_minifrontpage

best regards

Hello

I think you just need to write those overriden class into your gantry template css, maybe custom.css if any?

I Just put them into gantry-custom.css but they don't override the default one.

Anyway, can you tell me how to use suffix for individual stiling?
I added -comunicati to "Module Class Suffix" and created

.minifrontpage-default .mfp-introtitle-comunicati, .minifrontpage-default .mfp-introtitle-comunicati a {
/* display: inline-block; */
vertical-align: top;
color: #333333;
font: 300 80%/100% "Titillium Web";
text-transform: uppercase;
!important;
}

but it doesn't work.

Hi Can you share your website URL so I can take a look? Also please let me know what part you're trying to override