angular/adev/shared-docs/styles/_scroll-track.scss

@mixin scroll-track {
  // used on secondary nav
  .docs-scroll-hide {
    &::-webkit-scrollbar-track {
      background: rgba(0, 0, 0, 0);
    }
    &::-webkit-scrollbar {
      width: 0;
    }
  }

  // used for main page scroll
  .docs-scroll-track-transparent-large {
    &::-webkit-scrollbar-track {
      background: rgba(0, 0, 0, 0);
      cursor: pointer;
    }

    &::-webkit-scrollbar {
      width: 8px;
      height: 8px;
    }

    &::-webkit-scrollbar-thumb {
      background-color: var(--quinary-contrast);
      border-radius: 10px;
      transition: background-color 0.3s ease;
    }

    &::-webkit-scrollbar-thumb:hover {
      background-color: var(--quaternary-contrast);
    }
  }

  // used on table & secondary navigation
  .docs-scroll-track-transparent {
    &::-webkit-scrollbar-track {
      background: rgba(0, 0, 0, 0);
      cursor: pointer;
    }

    &::-webkit-scrollbar {
      width: 6px;
      height: 6px;
    }

    &::-webkit-scrollbar-thumb {
      background-color: var(--senary-contrast);
      border-radius: 10px;
      transition: background-color 0.3s ease;
    }

    &::-webkit-scrollbar-thumb:hover {
      background-color: var(--quaternary-contrast);
    }
  }

  .docs-mini-scroll-track,
  .shiki > code 
  // used on docs-code blocks
  {
    &::-webkit-scrollbar-track {
      background: transparent;
    }

    &::-webkit-scrollbar {
      width: 6px;
      height: 6px;
    }

    &::-webkit-scrollbar-thumb {
      background-color: var(--senary-contrast);
      border-radius: 10px;
    }

    &::-webkit-scrollbar-thumb:hover {
      background-color: var(--quinary-contrast);
    }

    &::-webkit-scrollbar-corner {
      background: transparent;
    }
  }
}