message: bring back global style rules for thin scrollbars (also FF now!)
diff: @@ -14,28 +14,31 @@ See the License for the specific language governing permissions and
  limitations under the License.
  */
  -.mx_AutoHideScrollbar {
  - overflow-x: hidden;
  - overflow-y: auto;
  - overflow-y: overlay; // where supported
  - -ms-overflow-style: -ms-autohiding-scrollbar;
  +// make any scrollbar grey and thin
  +html {
  + scrollbar-color: $scrollbar-thumb-color $scrollbar-track-color;
  +}
  +// scrollbar-width is not inherited (but -color is, why?!),
  +// so declare it on every element
  +* {
  + scrollbar-width: thin;
  +}
  - &::-webkit-scrollbar {
  +::-webkit-scrollbar {
  width: 6px;
  height: 6px;
  - background-color: transparent;
  + background-color: $scrollbar-track-color;
  }
  - &::-webkit-scrollbar-thumb {
  +::-webkit-scrollbar-thumb {
  border-radius: 3px;
  - background-color: transparent;
  - }
  -
  - scrollbar-color: transparent transparent;
  - scrollbar-width: thin;
  + background-color: $scrollbar-thumb-color;
  }
  +// make auto-hide scrollbars not transparent again on hover
  .mx_AutoHideScrollbar:hover {
  + scrollbar-color: $scrollbar-thumb-color $scrollbar-track-color;
  +
  &::-webkit-scrollbar {
  background-color: $scrollbar-track-color;
  }
  @@ -43,5 +46,22 @@ limitations under the License.
  &::-webkit-scrollbar-thumb {
  background-color: $scrollbar-thumb-color;
  }
  - scrollbar-color: $scrollbar-thumb-color $scrollbar-track-color;
  +}
  +
  +// make scrollbars transparent for autohide scrollbars
  +.mx_AutoHideScrollbar {
  + overflow-x: hidden;
  + overflow-y: auto;
  + overflow-y: overlay; // where supported
  + -ms-overflow-style: -ms-autohiding-scrollbar;
  +
  + &::-webkit-scrollbar {
  + background-color: transparent;
  + }
  +
  + &::-webkit-scrollbar-thumb {
  + background-color: transparent;
  + }
  +
  + scrollbar-color: transparent transparent;
  }
  