To make your application look the same for all devices, use HTML5 and CSS (which you already use with PhoneGap, fix it?)
You have to decide whether you want your Android application to look like your iPhone application, or if you want it to look different in an Android application, or if you want it to look like your application, regardless platforms.
No matter which route you take, the key to this is to use well-written and well-formed HTML and CSS. When I say well written, I mean that you don’t need to have any layout or style depending on the HTML and do all the layout and style using CSS.
From my personal experience, you're on the right track with a percentage / em.
sencha.io, . , , CSS HTML5.
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