[exaltedwombat]

If you're trying to set up the common style of indenting all paragraphs but the first, is there any reason not to simply use:

p { text-indent: 0; margin: 0.5 em 0 0 0; }

p + p { text-indent: 1.7em; margin: 0; }

Though the margin-bottom setting of your h1 etc. style should take care of spacing above the first lines of a chapter or titled section.