Thin Vertical Scrollbar

Here's a block of CSS that will generate a thin vertical scrollbar:

.scroll-thin {
  overflow-y: auto;

  /* Firefox */
  scrollbar-width: thin;
  scrollbar-color: rgba(0, 0, 0, 0.3) transparent;
}

/* WebKit Browsers */
.scroll-thin::-webkit-scrollbar {
  width: 4px;
}

.scroll-thin::-webkit-scrollbar-track {
  background: transparent;
}

.scroll-thin::-webkit-scrollbar-thumb {
  background-color: rgba(0, 0, 0, 0.3);
  border-radius: 10px;
}