Making background fixed (no scrolling) can't find CSS setting

I’m trying to fix the background of sl-freight.com. I know how to fix a background image with background-repeat:no-repeat; to not scroll but I’m not seeing where to do it in this particular style sheet.

The background image that is being used is called countryside.jpg and as you can see it does not show up in style.css

Here is the style.css:

/*
Theme Name: Tachyon
Theme URI: https://www.rockettheme.com
Description: RocketTheme Tachyon Theme for WordPress
Version: 1.0
Author: RocketTheme, LLC
Author URI: https://www.rockettheme.com
*/
a.rollover {
	display: block;
	width: 294px;
	height: 200px;
	text-decoration: none;
	background: url("https://sustainablelogistics.us/sl/rate-quote.png");
	}

a.rollover:hover {
	background-position: -294px 0;
	}
a.rollover2 {
	display: block;
	width: 294px;
	height: 200px;
	text-decoration: none;
	background: url("https://sustainablelogistics.us/sl/customers.png");
	}

a.rollover2:hover {
	background-position: -294px 0;
	}
a.rollover3 {
	display: block;
	width: 294px;
	height: 200px;
	text-decoration: none;
	background: url("https://sustainablelogistics.us/sl/carriers.png");
	}

a.rollover3:hover {
	background-position: -294px 0;
	}
a.rollover4 {
	display: block;
	width: 200px;
	height: 245px;
	text-decoration: none;
	background: url("https://sustainablelogistics.us/sl/4.png");
	}

a.rollover4:hover {
	background-position: -200px 0;
	}
a.rollover5 {
	display: block;
	width: 200px;
	height: 245px;
	text-decoration: none;
	background: url("https://sustainablelogistics.us/sl/5.png");
	}

a.rollover5:hover {
	background-position: -200px 0;
	}
a.rollover6 {
	display: block;
	width: 200px;
	height: 245px;
	text-decoration: none;
	background: url("https://sustainablelogistics.us/sl/6.png");
	}

a.rollover6:hover {
	background-position: -200px 0;
	}
a.rollover7 {
	display: block;
	width: 200px;
	height: 245px;
	text-decoration: none;
	background: url("https://sustainablelogistics.us/sl/7.png");
	}

a.rollover7:hover {
	background-position: -200px 0;
	}
a.rollover8 {
	display: block;
	width: 200px;
	height: 245px;
	text-decoration: none;
	background: url("https://sustainablelogistics.us/sl/8.png");
	}

a.rollover8:hover {
	background-position: -200px 0;
	}

.displace {
	position: absolute;
	left: -5000px;
	}