Oracle  ALTA UI  Skin  For  New  Development :

USING THE ORACLE ALTA UI SKIN FOR NEW DEVELOPMENT

New skin for ADF in 12c looks great, I have applied it for one of my sample application with ADF UI Shell and it works smoothly. Check Oracle documentation how to apply Alta UI, really easy.

ADF UI Shell with Alta UI - clean and light:

The Oracle Alta UI skin is meant for new development and is an opt-in. To use Oracle Alta UI skin instead of Skyros, there are a few configuration steps. You configure your application to use the new skin by specifying values for the <skin-family> and <skin-version> elements in your application's trinidad-config.xml file, as shown below.

To apply an ADF skin to an application

1. In the Applications window, double-click the trinidad-config.xml file. By default, this file is in the Web Content/WEB-INF node.
2. In the source editor, write entries to specify the value of the <skin-family> element and, optionally, the <skin-version> element as shown in the example below.

<?xml version="1.0" encoding="windows-1252"?>

<trinidad-config xmlns="http://myfaces.apache.org/trinidad/config">

    <skin-family>skyros</skin-family>

      <skin-version>v1</skin-version>

</trinidad-config>

The values that you specify for the <skin-family> element and, optionally, the <skin-version> element in the trinidad-config.xml file determine the ADF skin that the Fusion web application uses at runtime.