To insert a custom logo in the back office:

1. Click on Setup > Account > Custom domains from the main menu
2. Click on New from the context menu
3. Enter the host in the Custom domains section
4. Insert the logo in the Customize the look and feel section
5. Click on Save

The maximum file size is:

• 200 x 45 pixels for the Classic version
• 130 x 30 pixels for the Horizon version. Alternatively, modifying the CSS through the #DivAzienda selector (removing the paddings) can also fit 200 x 45

To change the file size it is better to use paint.net

If you customize the style of PMP forms, see also Custom graphics for PMP forms with the Midnight look.