How Can I Change Global CSS

[muraterdogann]

Hey There,

My website has a Slick-Slider which is not full screen at this moment. I want to do it full screen. So when I inspect the website I can see this code;

@media (min-width: 768px)
.col-md-9 {
flex: 0 0 75%;
max-width: 75%;
}

This code comes from Global.css which I dont have it in my theme folders.
When I change max-width to 100% on inspect slider becomes full screen when I paste this code to my css file nothing happens. How can I mport this code to my CSS?

Thanks.