I am trying to make my webpage's content start about 10cm (3.93 inches) from both sides with a border around them. The border thing I have under controll. It is just the content spacing on the sides. This link: Click Here has what I want but I dont know I to make my page like that.

something like

body {margin:5%;padding:5%;border:1px;}
p {margin:1%;margin-left:4%;}
p:first-line {font-weight:bold;margin-left:3%;}
p:first-letter {font-size:160%;}

The phone I am writing on has a screen only 9cm wide, 10cm borders mean blank screen.
Fixed dimensions mean a large number of potential viewers wont see the site as intended, and will leave
translating the layout from fixed to scalar, em and % dimensions wont take much at design stage, but will make viewable to the limitation of the users hardware, not limited by the design. also will be disabled friendly and self adjusting