La solution la plus simple est d'ajouter un style spécifique à Microsoft (dans le fichier HTML) comme suit:
<html>... <style> br { mso-data-placement:same-cell; } </style> ...</html>
Merci à Michu (24/7 dev & coffee blog) pour le tuyau!
Ref: Generating Excel files from web - line breaks in cells
Thanks to Michu for the great tip... Initial text copied here for convenience...
Generating Excel files from web - line breaks in cells
...I needed to wrap text in cell, but when I put tag into HTML output, Excel interpreted it as a new row, not a line-break in existing cell. The solution I found is to add into a stylesheet:
br {mso-data-placement:same-cell;}
