Gioia

In the case this may help someone else, I finally found a solution to this issue: maybe it’s not the most proper one, but it definitively works and it’s really easy!
After several attempts to stop my div layers by changing their properties (position, margins etc.)I decided to do the opposite, i.e. I put my header image into another div layer. I gave to this layer an absolute position and proper margins (as I did with all the other div layers) and then I put a z-index value of 0; then I gave to all the other layers an increasing z-index value (1; 2; 3 etc.). That’s it. At least, it works with all screen resolutions and with IE as well.

I apologize for the huge code posted.

This is my pastebin for my header code: http://pastebin.com/m5387c8c0
This is my pastebin for my sidebar: http://pastebin.com/m3a88c793
And this is my pastebin for my css (just the section beloning to this issue): http://pastebin.com/m379c602

Thanks in advance.