how to add custom borders around the page code example

Example: how to add custom borders around the page

Markup:

<div id="left"></div>
<div id="right"></div>
<div id="top"></div>
<div id="bottom"></div>

Styling:

#top, #bottom, #left, #right {
	background: #a5ebff;
	position: fixed;
	}
	#left, #right {
		top: 0; bottom: 0;
		width: 15px;
		}
		#left { left: 0; }
		#right { right: 0; }
		
	#top, #bottom {
		left: 0; right: 0;
		height: 15px;
		}
		#top { top: 0; }
		#bottom { bottom: 0; }