I'm looking for a CMS which could handle the following:

I must create a website which will use a global template to define it's layout. This template should have some different regions. By example:
+----------------------+
| 1 |        2         |
+---+------------------+
|   |                  |
| 3 |        4         |
|   |                  |
+---+------------------+

Region 4 will contain the actual content of the site.
Now, the first problem is that for every page it should be possible to select a background image for region 1, 2, 3, and also change their width/height and padding.

The second difficulty is the actual content. This should also be defined by some kind of 'inner-template'. With 'inner-template' i mean the following:
To lay-out the content of every page you have some templates available, from which you choose one for every page. Those templates simply define content-blocks, which can be edited one-by-one with a wysiwyg editor. Two examples:

+---------------------+     +-------+-------------+
|                     |     |       |             |
+----------+----------+     |       |             |
|          |          |     |       +-------------+
|          |          |     |       |             |
|          |          |     |       |             |
+----------+----------+     +-------+-------------+

So in the end this should result in the following scenario for the site owner when he wants to add or edit a page:
  - He creates a new page or chooses to edit one.
  - He can modify the general template, with specific changes for that page (other background-image in the header etc)
  - He chooses an inner-template (=content-template) which is used inside the content-region (in my example that would be block 4)
  - He can edit every content-block from the content-template using a built-in wysiwyg-editor

Is there a CMS available with which i could create something like this?

thx in advance!!