body 				{ font-size:62.5%; } /* now 10 px is 1 em*/
p.px				{ font-size:12px; }
p.px a				{ font-size:10px; }
p.em				{ font-size:1.2em; } /* 12 px eq */
p.em a				{ font-size:1em; } /* 10 px eq? actually no, it is still 12px, as it is 1 em out of the parent which is 12 px eq */
p.em a				{ font-size:0.83em; } /* 10 px out of 12 px is 83%, so for a link to be 10 px equivalent, we need to set the size to .83 */