Styling in NativeScript is combination of CSS, Layouts and the appropriate images.
You change the looks and appearance of views (elements) in a NativeScript application similarly to how you do it in a web application—using Cascading Style Sheets (CSS) or changing the style object of the elements in JavaScript. Only a subset of the CSS language is supported.
Similarly to the DOM Style Object, each View instance exposes a style property, which holds all the style properties for the view. When the view is displayed, all its style properties are applied to the underlying native widget.
Additionally, in the video below, you can watch the NativeScript Air podcast dedicated entirely to Building Attractive UIs in NativeScript.