Make the window border in Split stand out more

[bungadrum]

When you activate Split view the window border is very small and you can barely see it. When you use your keybord or mouse to navigate it's hard to figure out where you currently are. Can you add option in settings to make the border radius for tabs in split view bigger and to add a custom color. It is similar to what PopOS latest Cosmic desktop has something along those lines

You can barely see anything like this:

It could look like this: