Reduce template width

Hello friends,

I’m using the template Codilight Lite in my website with some design adjustments. I’m trying to reduce the width of the website, leaving only the header in full size. I’ve tried do adjust the following code, changing margin-right and letf to 12.5% each, so the body of the website uses only 75% of the browser screen.

The method worked fine in my desktop, but it also changes the width in the mobile version, which makes my blog looks terrible in smaller devices.

How can I change the size of my blog only in the desktop version?

My website is: softler.com.br

.container {
	margin-right: auto;
	margin-left: auto;
	padding-right: 25px;
	padding-right: 1.5625rem;
	padding-left: 25px;
	padding-left: 1.5625rem;
}

Thanks!