message: fix: move gutters behind overlays
diff: height: 100%;
  overflow-y: auto;
  // Must be lower than the drawer's z-index
  - z-index: 15;
  + z-index: 2;
  &[data-gutter-closed='true'] {
  transform: translateX($modifier * 100%);
  #{$side}: 0; // Fix side to the edges of the parent element
  height: 100%;
  overflow-y: auto;
  - z-index: 20;
  + z-index: 3;
  // Display a box shadow to either side when opened
  &[data-gutter-closed='false'] {
  