Informations tree

Hi.

I've to show contents of a page in this format:
------------------------------------
TitleA
- contentA1
- contentA2
TitleB
- contentB1
- contentB2
- contentB3
.....
------------------------------------

To do this I use <div> tag and attribute style set on 'none'.
This is the classic tree to expand.

My question is: does the spider of search engine consider it
like hidden text? Is this method dangerous to use?
How can I display informations for users without problems?

Thank you very much,
Matteo Migliore.

MSN - dynamichardware (AT) email (DOT) it
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