The body has this transition: 'transition: background-color 0.3s ease
0s'. Making the scrollbar-track background-color transparent allow us to
appreciate that transition in the scrollbar-track when switching the
background-color.
This change will make the vertical scrollbar styles to follow the dark
and light color scheme modes. Also, this change will make the vertical
scrollbar to look consistent in both, Chromium and Firefox.
