Screen size on mobile devices


I'm trying to get a newly added interactive application running on amobile device (such as an iPhone).
It should run directly in a browser (e.g. Safari or Chrome).
This I used the parameterizes URL functionality to call the application within the browser.
So far it worls fine but the E1 Screen gets sized automatically.
The result is Webpage which Shows the application itself very small. In the upper right Corner the Webpage Displays the Default info/help Buttons.
But inbetween there is a lot of whitespace...
Is there a possibility to downsize the Webpage to a specific size (e.g. 400px in width instead of 100% of the available screensize)?
I tried to tune the style Sheets but got lost...

Thanks for any tips,

E1 9.1 TR 9.1.4 Weblogic