For years Neptune featured a simple and easy on the eyes design that has been improved over the years.
With Neptune 4.0 we planned to modernize the design and completely revamp it without loosing the touch of simplicity and easy going.

Introducing the new Neptune 4.0 Design (Work In Progress):

ksplash
KSplash

The new KSplash shows the main new color of Neptune 4.0. That being a lightball in a greyish universe.
In the center of that universe you see the Neptune Logo and underneath it a subtle blueish progressbar showing the progression of the Plasma Desktop start.

desktop
Desktop

The Desktop is the the center of the work most users do on the Neptune system. We aimed to create a distract free desktop experience by using elements of the ksplash greyish universe centered around the Neptune logo together with a dark grey bottom panel holding the big universe on its shoulders. Slightly improved Neptune Faenza Icons help to maintain a good contrast even on the panel so that every icon is distinguisable from the another and clearly visible to the eyes of the user.

Window
Window

The Window features the same slick and easy to the eyes greyish color with a high contrast in the titlebar and a strong black shadow showing how light the window is as it keeps flowing over the desktop.

mouse-cursor
Mouse Cursor

The mouse cursor brings a breeze into the light and greyish universe. Thanks to phenomenal work of the KDE Visual Design Group who made this nice and good looking cursor theme.

All in all I hope you like the new design idea of Neptune 4.0 Work is still ongoing to improve it even more and we would like to hear your feedback either as a comment or in the forum.