[SOLVED] Custom style only being applied to first line of text.

Hi. Thanks for a great theme and a great forum.
I'm halfway through a site, but I've hit a snag.

I can't get CSS inserts to change anything other than the first line of text in a given paragraph of the centre column.

I have made custom <h8> tags and a custom class as per the HOWTO: make a custom text style on post/page sticky but neither work properly other than on the first line of text. How do I get it to apply to all the text I span?

Cheers,
Mick