title: CSS - Setting padding/margins based on text-width?
body: <p>Is there a measuring unit in CSS (either planned or already in existence) for setting the padding and margins based on the width of the font being used?</p>
  
  <p>I know that <code>em</code> is supposed to be the height of the upper-case M of the font the browser uses, which is really handy for adding a clean double-spacing. But I sometimes want the side-margins of inline lists to be the width of a normal non-breaking space, or the width of an upper-case A. With some fonts, using em is vary unreliable.</p>