xdaseinx on "[Plugin: WordPress Related Posts] css modern default theme editing"

You can use the custom option and paste this in:
You have to change the background of the .related_post_title. Let me know if you need help.

.related_post_title {
	background: rgba(245, 245, 245, 1) !important;
	padding: 3px 0 3px 10px !important;
	margin: 0 !important;
	font-weight: normal;
	border-radius: 2px !important;
	border: 1px solid rgba(0, 0, 0, .1) !important;
	clear: both !important;
}
ul.related_post {
	margin: 0 0 18px 0 !important;
	padding: 0 !important;
}

ul.related_post li {
	overflow: hidden !important;
	list-style: none !important;
	padding: 10px 0 10px 0 !important;
	margin: 0 !important;
	border-bottom: 1px solid rgba(0, 0, 0, .1) !important;
	background: none !important;
}

ul.related_post li a {
	text-decoration:none;
}

ul.related_post li a img {
	width: 60px;
	height: 60px;
	float: left !important;
	margin: 0 10px 0 0 !important;
	padding: 0 !important;
	max-width: 100% !important;
}

ul.related_post li a.title {
	vertical-align: top !important;
}

/* override old CSS for new plugin version with CSS classes */
ul.related_post li a.wp_rp_thumbnail {
	float: left !important;
	margin-right: 10px !important;
}
ul.related_post li a.wp_rp_thumbnail img {
	float: none !important;
	margin-right: 0 !important;
	display: block !important;
}