The theme information can be accessed with:
/// Requires a reference to AdUiPalettes.dll
Autodesk.Windows.Themes.ThemeManager.Instance.PaletteSettings.CurrentTheme;
It's up to you to set the appropriate properties on UI elements (e.g., Foreground/Background color, etc.) to the values contained in the PaletteTheme object returned by this method. There's no 'easy button'.