Theme Setup - CSS Only

An alternative to creating a archive-listing.php and single-listing.php as discussed in Theme Setup is to use CSS. This solution is especially handy if there is no child theme in place. 

• See: Why you should always use a child theme with WordPress and how to create one.

This is some simple CSS you can use to centre the listings on the Search Results pages.

.epl-post-type-archive #sidebar,
.epl-single-listing #sidebar{
	display: none; /* Hide the sidebar but check the sidebar ID or class */
}
.epl-single-default,
.epl-archive-default {
	max-width: 1155px; /* Adjust Me based on theme max width */
	margin: 0 auto; /* Adjust Me based on theme max width */
	margin-top: 2em; /* Adjust Me based on theme max width */
}
@media screen and ( max-width: 1155px ) {  /* Adjust Me based on theme max width */
	.epl-single-default,
	.epl-archive-default {
		padding-left: 1em;  /* Adjust Me based on theme max width */
		padding-right: 1em;  /* Adjust Me based on theme max width */
	}
}

Before where listings are stretched to the browser edges:

After implementing the CSS

Note: This solution hides the Sidebar. It can be re-added also with CSS, however a bit more CSS will be involved as many themes are coded with sidebar/minimal sidebar support. It might be easer to do a full Theme Setup then to tackle sidebar positioning with CSS.

Uncommented CSS

.epl-post-type-archive #sidebar,
.epl-single-listing #sidebar{
	display: none;
}
.epl-single-default,
.epl-archive-default {
	max-width: 1155px;
	margin: 0 auto;
	margin-top: 2em;
}
@media screen and ( max-width: 1155px ) {
	.epl-single-default,
	.epl-archive-default {
		padding-left: 1em;
		padding-right: 1em;
	}
}