Navigation links float problem

Hi all,
I am customizing the WP default theme templates for my italian weblog. So far so good, I managed to modify the header and sidebar code properly, and I’m working on the content area. Most of my customization happens in the header template, which is working as intended.

One problem here: for some strange reason I cannot seem to float properly the Previous and Next navigational links at the bottom of the index page, and also the ones at top for the individual post page (based on the single.php template). The php seems to work, it’s probably just a XHTML/CSS problem: I checked it all multiple times, but I still can’t see where the conflict is.

The structure of my index.php and single.php templates is quite similar to the corresponding default templates: the Previous and Next php functions are wrapped in 2 DIVs (.alignleft and .alignright), both wrapped in a .navigation DIV. All these 3 DIVs are sitting inside the #content DIV which is floated left, exactly as in the default theme.

In my style.php file the .alignleft class has a float:left declaration, and the .alignright class is floated right. Exactly as in the default theme!

So why those silly 2 DIVs refuse to float properly? They sit one under the other in my single post page, no matter what I try to do.

What could be the problem? I am going a bit crazy about this detail, I hate when I can’t see the cause.

Here is the URL of my blog, where you can check the glitch for yourself, both on the index page and in the single post page:

http://www.tomblog.it

And here is the direct link to my CSS page:

http://www.tomblog.it/wp-content/themes/custom/style.css

Any help appreciated, thank you guys.

Paolo