If you read through the release notes page 13, it specifically says that the logo sizes have changed. They are now 300x48 and 200x28 with ZCS 7 rather than the 450x100 and 120x35 of version 6.
Updating Customized Themes in 7.0
In ZCS 7.0, the themes were updated and the logo banner sizes have changed.
If you modified ZCS themes to add your logo to the logon page, splash screen and ZWC, you will need to adjust the logo sizes to fit the new layout.
•For the company logo that displays on the login and splash screens in ZWC and ZCS administration console the dimension of the graphic must be exactly 300 x 48.
•For the small company logo in the upper-left of the ZWC application and the administration console, the dimensions the graphics must be exactly 200 x 28.
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