Custom Logo : why so small, blurry output, why?

Issues re: custom logo ..

When (in Writer, for instance) accessing Admin Console, and uploading a custom logo, there is NO information about the required logo size and format -- please add such basic information in the interface so we don't waste our time. By the way, what IS the required size and format of the custom logo???
By rooting around in the forums I've found some references to the logo size, and have tried those, but each time the logo comes out a) TOO SMALL for any practical use, and b) BLURRY... i.e. not sharp like the image I've sized and uploaded.

Since I have an actual business to run and am trying to make the move from Google Apps to Zoho Apps, could this basic feature be improved so that it is meaningful and works well? I'm a big fan of Zoho and a Zoho Creator developer. Am trying to see if the other Zoho Apps are usable yet. Would love to migrate my business away from Google, but need Zoho to be fundamentally together.

Many thanks.

datazen1@gmail.com
Santa Fe, New Mexico US