Hey everyone do you know of a design guide for

Question

Hey everyone do you know of a design guide for

list elements? I am trying to design ui for a productive tool I have written. I have created some designs but they don't look good imo. I'd welcome suggestions on how to improve it, or even rework on it.

The main elements of the app is the timer, close button, and a list of elements (application windows currently visible). The idea is that you will be able to select windows and if the foreground window (or the window in focus) is the same as the selected on, it will keep the timer running. else the timer will pause.
If you're interested on how it works, here (Devs Chat group): https://t.me/c/1142198149/501387

Btw its a windows only application