How to add border to DOM element from the component logic using insertAdjacentHTML?

Question

I am trying to add a border of 2px solid from my component logic, meaning, from the component.ts.

Could you help me ? Thank yous for your time ?

I am expecting to just frame a simple div.

I tried using insertAdjacent as in this stackblitz project :

I have tried doing this :

https://stackblitz.com/edit/angular-ivy-5jrpwv?file=src/app/app.component.html

but I get no results.