Maybe something from your postfix tutorial fubard it?
I don't see how adding the email settings would have this effect.
Did you add any extensions? Custom headers in appearance settings?
Please enable debugging:
sudo nano /var/www/cyc/config.php
Change debug from false to true.
When it says something went wrong, you will have a debug option.
You can always start from scratch in the morning. ?
Oh and you will get the white site with out css with a simple typo. Make sure you recheck you edits.