Is there a way of making the Active Tab Border highlighted on top instead of at the bottom?

Solution 1:

You can visit the Theme Color VS Code web page to get more information on this.

Open your user settings.json (Ctrl + ,)

Two lines below the tab.activeBorder, you will find tab.activeBorderTop, which does exactly what you intended.

"workbench.colorCustomizations": {       // Can customize each aspect
    "[One Dark Pro]": {                  // Optional
        "tab.activeBorderTop": "#0A84FF" // Active Tab Top Highlighting
    }
},

Solution 2:

you can add this to .vscode/settings.json

"workbench.colorCustomizations": {
    "tab.activeBorder": "#ff0000",
    "tab.unfocusedActiveBorder": "#000000"
}

Solution 3:

You can also colorize background of tab:

"workbench.colorCustomizations": {
    "tab.activeBackground": "#0000ff"
}