message: Get rid of annoying flash of line when top edge is opening
diff: /* these classes comes from the ember-sidebars addon. We need to
  increase the z-indices of the sidebars so they stay on top of the
  scrims provided by ember-overlays. */
  -.cst-right, .cst-top, .cst-left {
  +.cst-right, .cst-left {
  z-index: 100;
  }
  +.cst-top {
  + z-index: 100;
  + right: -1px;
  +}
  +
  .cst-bottom {
  z-index: 150;
  }
  