@jimboh1978 this has been asked multiple times in the forum (maybe we should add this at the top in the css forum).
But anyways, you adjust the body margin and width/height
(This will be added in the custom.css file, and not altered in the main.css)
This will add a 100pixel border around the entire screen
body { margin: 100px; height: calc(100% - 200px); width: calc(100% - 200px); }This will add a 100pixel border on the sides and 50pixel border on top and bottom
body { margin-right: 100px; margin-left: 100px; margin-top: 50px; margin-bottom: 50px; height: calc(100% - 100px); width: calc(100% - 200px); }Notice that you always have to subtract the totalt border width (left+right) and/or height (top+bottom) to get to display properly.