Actually, Im using just a simply code border.
[spoiler]/* MASTER BORDER */
body {
border-color: #HEX COLOR;
border-width: 30px;
border-style: groove;}[/spoiler]
but you can also use bobcbar, and j_luitan idea.
Also, you can combine all your body codes like the scrollbars, and wallpaper.
More complex.
[spoiler]/* BODY */
body {
background-image: url(IMAGE URL);
background-attachment: fixed;
background-position: center;
background-repeat: no-repeat;
background-color: #Hex Color;
border-top-color: #Hex Color;
border-bottom-color: #Hex Color;
border-left-color: #Hex Color;
border-right-color: #Hex Color;
border-top-width: 0px;
border-bottom-width: 0px;
border-left-width: 0px;
border-right-width: 0px;
overflow-x: display;
scrollbar-face-color: #Hex Color;
scrollbar-highlight-color: #Hex Color;
scrollbar-shadow-color: #Hex Color;
scrollbar-3dlight-color: #Hex Color;
scrollbar-arrow-color: #Hex Color;
scrollbar-track-color: #Hex Color;
scrollbar-darkshadow-color: #Hex Color;}[/spoiler]
Or try to read some tutorials. Search in google.