In order to quickly create a native iOS-like UI of a PhoneGap app, perform the following steps:
Open the first ever developed iOS web app: Change the user agent of your browser and navigate to the iPhone user guide available on the Apple Developer site http://help.apple.com/iphone/; you will load in the browser HTML and CSS that really look similar to a native app.
Grab the CSS and the images: Open the Web Inspector and download all the images from the Resource panel; locate and grab the CSS file from the Network one (or pull the project from GitHub https://github.com/cheeaun/hnmobile).
Use the CSS and the images in your project: Change the CSS file according to your needs and use it across the view of your app.
You created the building blocks of the styles of your app for iOS. As you can see from the following screenshots, the results look great and approximate a native app look and feel: