page-break-before:always should work in the sense of forcing a pagebreak before the number, so that the section will start at the top of a page and it would be very unlikely to have another pagebreak right after that (unless the next element is a very large image, for example).
If it doesn't work, either there's some problem in the CSS (are you sure it's being used at all? can you make the number bold/italic/underlined?) or the reader is just ignoring pagebreaks, and as far as I know ADE does not do this.
(page-break-inside:always makes no sense)
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