Recently, I came across a cool extension which allows me to customize Visual Sutdio Code CSS, hence allows me to play as I wish with the UI.

So I went for an aesthetic fresh look of rounded corners with subtle shadows and It turned out pretty cool !

Here are the settings and the instructions :

Add to your user settings JSON file the custom-ui-style.stylesheet (you need to use this extension or use other extension which allows you to customize VS Code UI using CSS), you will also need to match the colors, or it will look weird, so this is this part "workbench.colorCustomizations".
Make sure not to replace the entire settings JSON file because you might have other unrelated settings there for your extensions.
I did clean up a bit this settings file to not include unrelated settings.