Customizing the scroll bar

I’ve brought this up before and got a helpful answer (thank you), but I’m applying this code to quick messages input composer and nothing’s happening.

      -webkit-appearance: none;
      width: 10px;
    }

    &::-webkit-scrollbar-thumb {
      cursor: pointer;
      border-radius: 5px;
      background: dark-light-choose($primary-medium, $secondary-medium);
    }

    &::-webkit-scrollbar-track {
      background: transparent;
      border-radius: 0;
    }