Adding horizontal lines between different Sidebar-Widgets

With the help of emilyTK – https://wordpress.org/support/topic/different-background-colours-for-different-sidebar-widgets?replies=3#post-6029793 – I decided finally for borders:

div#secondary aside:nth-child(1n+1){
	border: 1px solid #8B008B;
  	padding: 0 10px 10px 10px;;
}

But with two slight changes it’s also suitable for horizontal demarcation lines only:

div#secondary aside:nth-child(1n+1){
	border<strong>-bottom</strong>: 1px solid #8B008B;
  	padding: 0 10px <strong>25</strong>px 10px;;
}

Cfr. http://1a-spielwiese.de/wp-content/uploads/2014/09/Sidebar_horizontal_lines.jpg