desktop + touchkit application

I have an existing web application with Vaadin. now I would like to add mobile support for this app. 
As soon as I add the dependency on my pom.xml and compile the weidgetset of the touchkit, my application behaves differently on the desktop (loading looks different and component positioning changes) I don't want to change my desktop application how do I do that ?

second question:
what's the best practice ? should I add another UI for the mobile users ?

Thanks

Yinon Shiryan:
what's the best practice ? should I add another UI for the mobile users ?

Thanks
 

Yes, with TouchKit that is they way to go.