Custom logo illegible when re-sized in webclient

The default login page and web client suits our need, we'd just like to replace those logo assets.

When defining a custom logo in the admin panel it looks great on the login page, but that same asset is resized for display on the web client and becomes nearly illegible.

As a work around, I found and replaced the logo files; however, the server understandably fails an integrity check and prompts for a re-install.

Is there an solution or work around for defining a second appropriately sized logo for display in the web client?

Thanks

FrankD

edit*

Serv-U ver 15.1.0.458