In 7.31 SP14 / 7.4 SP9 a new feature was introduced Ajax Framework Page in IE standards mode
This feature allows you to run standards based content e.g HTML5 / UI5 / Fiori applications inside the AFP Shell.
This is the reason why in 7.31 SP16 / 7.4 SP11 we introduce AFP Standards with SAP Blue Crystal theme and Fiori User Experience.
The Blue Crystal theme will only be supported while using AFP in standards mode because it was designed for UI5 and Fiori applications.
New visual design for the pop-up
New visual design for the role entries in the TLN and overflow buttons.
Notice that the Detailed Navigation (DTN) is now without the curves you used to see in bottom and top right side.
New parameters for the background colors of those elements were exposed for the UI Theme Designer allowing you to easily customize the theme.
In the following screenshot you can see a very small example of theming possibilities (as you imagine no designer will pick these colors 
)
We tried to keep this theme as lean as possible and to adhere to the simple clean look of Fiori User Experience.
Hope you like it.