I have updated my site to SMF 2.0.
I am using a quite big logo with curve theme and I need to increase the height of the area in which the logo must fit (you can clearly see it in the image attached).
Thank you in advance!
If you want to increase the height of the light blue strip at the top of the header, you have to edit the background image - /Themes/default/images/theme/main_block.png.
You can increase the overall header height in /css/index.css by editing #top_section.