Answers for "how to hide scrollbar when not scrolling"

css hide scrollbar but allow scroll

html {
  overflow:   scroll;
}
::-webkit-scrollbar {
    width: 0px;
    background: transparent; /* make scrollbar transparent */
}

css hide scrollbar

// Sass Mixing
@mixin hideScrollbar {
  &::-webkit-scrollbar {
    width: 0 !important
  }
  -ms-overflow-style: none;
  scrollbar-width: none;
}