Logo width change

In order to decrease "Quick Access" area open /YourMagentoDir/skin/frontend/default/YourSkin/css/skin.css.
Add following code to the end of skin.css file

Another way: you can instert logo picture in the header background.

You will need to create transparent logo.gif to replace current logo.

Please open
[YourMAgento]/skin/frontend/default/storeblack/images/header_bg.jpg
file to edit in the image editor (for example, Photoshop). You can insert you logo here.

The logo image height is 90px

Don't forget to change Logo ALT tag here:
System-->configuration-->General-->Design (tab)--> Header (tab)