[Solved] Add margins around maximized windows? (Plasma 6)

I'm trying to add margins around all maximized windows (so that it matches my custom taskbar which also have small margins all around), any ideas how to achieve this? I tried doing a KWin script, but even though it installs and activates, it doesn't work, not sure what's wrong. Also I have suspicions there might be easier ways to do it. This is my script attempt:

workspace.clientMaximizeSet.connect(function(client, h, v) {
    if (h && v) {
        client.frameGeometry = {
            x: 0,
            y: 4,
            width: workspace.displayWidth - 4,
            height: workspace.displayHeight - 8
        };
    }
});

Found solution: I already have panel colorizer widget for KDE Panel and it turns out, I could simply create extra panels on top/right/bottom edges with panel colorizers that allow to make them fully transparent and have custom height/width. And for windows to not lose borders/rounded corners when maximized I found a flag in "Window Decorations > Breeze" options.