.bff-overlay{
  position:fixed;top:50%;left:50%;
  transform:translate(-50%,-50%);
  font:900 22vh/1 var(--heading, sans-serif);
  color:#fff;
  text-shadow:0 0 20px var(--accent, #aa3bff), 0 0 46px var(--accent, #aa3bff);
  opacity:0;
  pointer-events:none;
  z-index:20;
  letter-spacing:.04em;
  user-select:none
}
.bff-overlay.flash{animation:bffFlash .45s ease-out}
@keyframes bffFlash{
  0%{opacity:0;transform:translate(-50%,-50%) scale(.7)}
  10%{opacity:1;transform:translate(-50%,-50%) scale(1.08)}
  22%{opacity:.55;transform:translate(-50%,-50%) scale(1)}
  100%{opacity:0;transform:translate(-50%,-50%) scale(1)}
}