If you want only the first paragraph after h1 to have this styling, get rid of the tilde and use the plus sign. Just use:
Code:
h1 +p {
font-size: 1.3em;
margin-top: 1em;
font-style: italic;
text-indent: 0;
text-align: center;
}
The plus sign can be used to style siblings for styled paragraphs, divs, blockquotes, etc. I have one frequently used one that looks like this:
Code:
.ind0,
.scndrop,
.scnbrk +p,
h2 +p,
h3 +p,
div.qnote p {
text-indent: 0em;
}
The ones with the "+" style the first paragraph that *follows* that tag. The last one listed, div.qnote p with no "+", styles all the paragraphs *inside* that div.
As far as I know, it is valid in epub2, and is supported very widely in devices and software.