The kiosk in MobiControl is defined with template in standard html/CSS/javascript.  Thus, layout design like font size, icon size, icon spacing, etc. can all be tuned just like any web page on a browser.  Also, CSS compliant statements in the template support definitions in a single template file multiple layout/style designs depending on the screen size/resolution of the device.

Consult an colleague/friend with web-page design experience, or read a good hands-on book for beginners and you should be able to do simple layout change in a couple of hours.

If you don't even have that time, you can simply experiment by cloning the default template, and modifying different items that have numbers followed by 'px'.  In general, reducing the number reduces the size or separation of certain visual object it controls.