As we mentioned last week, Ubuntu has improved the look of Ubuntu’s default themes when used in GNOME Shell
New updated versions of the Ambiance and Radiance GTK themes will feature in Ubuntu 17.10.
But you don’t have to wait until October to be use then. The updated Ambiance and Radiance themes can be downloaded and installed on earlier versions of Ubuntu.
The gif above shows how much of a difference the updated light themes makes under GNOME. It gives windows nicely rounded corners, drop shadows, and better spacing of elements within the CSD.
If you’re running Ubuntu 16.10 or 17.04 you can download the light themes installer package below. Keep in mind that this is from an in-development version of Ubuntu, which means it itself is a ‘development’ snapshot.
But we’re not talking about upgrading a critical part of your system here; it’s a theme, and if something untoward happens as a result of installing it you can, at any time, downgrade back to the version available in the 17.04 (or 16.10) repos.